The existing code started the timer once (and expired once) but didn't
properly handle re-starting of the timer. Neither did it handle
the 'half time expiration' case. If we want to call a function after
half the WT expiring, we must of course program the hardware for half
the timeout, and not the full timeout...
Change-Id: Ia999d97f835c27597fcd1cf7ac78bac0ab9c98c1
Related: OS#1704