staging: mei: renaming delayed work field and function to a meaningful name.

the wd_work and mei_wd_timer() function was not just for watchdog.
mei managing the AMT watchdog going to be replace by the kernel watchdog
interface.

the mei_timer() will still manage the mei driver timeouts.

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>