watchdog: Fix typo in pnx4008_wdt.c

Correct spelling "resouce" to "resource" in
drivers/watchdog/pnx4008_wdt.c

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>