cpwatchdog build fix

sparc64:

drivers/sbus/char/cpwatchdog.c: In function `wd_toggleintr':
drivers/sbus/char/cpwatchdog.c:523: error: implicit declaration of function `readb'
drivers/sbus/char/cpwatchdog.c:533: error: implicit declaration of function `writeb'
drivers/sbus/char/cpwatchdog.c: In function `wd_pingtimer':
drivers/sbus/char/cpwatchdog.c:545: error: implicit declaration of function `readw'
drivers/sbus/char/cpwatchdog.c: In function `wd_starttimer':
drivers/sbus/char/cpwatchdog.c:584: error: implicit declaration of function `writew'
drivers/sbus/char/cpwatchdog.c: In function `wd_init':
drivers/sbus/char/cpwatchdog.c:767: error: implicit declaration of function `ioremap'
drivers/sbus/char/cpwatchdog.c:767: warning: assignment makes pointer from integer without a cast
drivers/sbus/char/cpwatchdog.c: In function `wd_cleanup':
drivers/sbus/char/cpwatchdog.c:849: error: implicit declaration of function `iounmap'

Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>