[WATCHDOG] machzwd warning fix

From: Andrew Morton <akpm@linux-foundation.org>

drivers/char/watchdog/machzwd.c: In function 'zf_ioctl':
drivers/char/watchdog/machzwd.c:327: warning: passing argument 1 of 'zf_ping' makes integer from pointer without a cast

Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>