watchdog: Give watchdogs a name ...

This adds a dev and name member to struct watchdog which helps distinguishing
between different watchdogs. Also add some debugging aids.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

watchdog: Allow multiple watchdogs ...

Put watchdogs on a list to allow multiple watchdogs. Add a priority
field to be able to pick the highest priority watchdog.
This patch also provides a of_get_watchdog_priority() function to
allow configuring the watchdog priority from the device tree.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Add a simple watchdog framework ...

This patch adds a simple wd command which can setup, trigger and stop a watchdog
on the platform.

Signed-off-by: Juergen Beisert <jbe@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>