staging: mei: adding watchdog ping

adding watchdog ping to send ping/heartbeat to the the AMT watchdog client.
in addition removing the heartbeat sending from the driver timers function.

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>