capi: fix sparse warnings using integer as NULL pointer

drivers/isdn/capi/kcapi.c:829:30: warning: Using plain integer as NULL pointer
drivers/isdn/capi/kcapi.c:838:27: warning: Using plain integer as NULL pointer
drivers/isdn/capi/kcapi.c:954:17: warning: Using plain integer as NULL pointer
drivers/isdn/capi/kcapi.c:1007:37: warning: Using plain integer as NULL pointer
drivers/isdn/capi/kcapi.c:1009:33: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capiutil.c:453:24: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capilib.c:47:30: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capi.c:353:29: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capi.c:369:15: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capi.c:486:48: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capi.c:515:46: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capi.c:541:47: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capi.c:692:47: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capi.c:699:49: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capi.c:704:14: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capi.c:943:53: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capi.c:948:32: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capi.c:969:42: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capi.c:989:48: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capi.c:1026:69: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capi.c:1028:19: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capi.c:1061:20: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capi.c:1529:37: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capi.c:1531:33: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capidrv.c:338:15: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capidrv.c:758:32: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capidrv.c:880:40: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capidrv.c:407:15: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capidrv.c:429:49: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capidrv.c:407:15: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capidrv.c:444:49: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capidrv.c:429:49: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capidrv.c:429:49: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capidrv.c:429:49: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capidrv.c:429:49: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capidrv.c:429:49: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capidrv.c:1664:61: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capidrv.c:1969:37: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capidrv.c:2294:37: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capidrv.c:2297:33: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capidrv.c:2338:37: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capidrv.c:2341:33: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capifs.c:192:37: warning: Using plain integer as NULL pointer
drivers/isdn/capi/capifs.c:194:33: warning: Using plain integer as NULL pointer

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Cc: Karsten Keil <kkeil@suse.de>
Cc: Jeff Garzik <jeff@garzik.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>