[WATCHDOG] Documentation/watchdog/watchdog-api.txt - fix watchdog daemon

Fix the simple watchdog daemon program in Doc/watchdog/watchdog-api.txt
to build cleanly.

Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Signed-off-by: Andrew Morton <akpm@osdl.org>