We keep the old /dev/watchdog interface file for the first watchdog via
miscdev. This is basically a cut and paste of the relevant interface code
from the rtc driver layer tweaked for watchdog.

Revised to fix problems noted by Hans de Goede
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NHans de Goede <hdegoede@redhat.com>
Signed-off-by: NTomas Winkler <tomas.winkler@intel.com>
Signed-off-by: NWim Van Sebroeck <wim@iguana.be>