watchdog: watchdog_core: Add watchdog registration deferral mechanism

Currently, watchdog subsystem require the misc subsystem to
register a watchdog. This may not be the case in case of an
early registration of a watchdog, which can be required when
the watchdog cannot be disabled.

This patch introduces a deferral mechanism to remove this requirement.

Signed-off-by: Jean-Baptiste Theou <jtheou@adeneo-embedded.us>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

diff --cc Documentation/watchdog/watchdog-kernel-api.txt
Simple merge

diff --cc drivers/watchdog/watchdog_core.c
Simple merge

diff --cc include/linux/watchdog.h
Simple merge