staging: mei: registering the MEI driver with the kernel watchdog core interface

Adding kernel watchdog interface (/dev/watchdog) to the MEI Driver to support AMT Watchdog feature.
This patch and the following one will replace MEI Driver self management of the AMT watchdog
with the standard kernel watchdog interface.

Signed-off-by: Oren Weil <oren.jer.weil@intel.com>
Acked-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>