watchdog: sb_wdog: Make sbwdog_set and sbwdog_pet static
Fix sparse warning:
drivers/watchdog/sb_wdog.c:70:6: warning: symbol 'sbwdog_set' was not declared. Should it be static?
drivers/watchdog/sb_wdog.c:84:6: warning: symbol 'sbwdog_pet' was not declared. Should it be static?