drm/i915/guc: Enable the timer expired interrupt for GuC

The GuC can implement execution qunatums, detect hung contexts and
other such things but it requires the timer expired interrupt to do so.

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
CC: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210727002348.97202-15-matthew.brost@intel.com