Now that the error capture is fully decoupled from fence signalling
(request retirement to free memory, which in turn depends on resets) we
can safely flush the G2H handler during a GT reset. This eliminates
corner cases where GuC generated G2H (e.g. engine resets) race with a GT
reset.

v2:
 (John Harrison)
  - Fix typo in commit message (s/is/in)
Signed-off-by: Matthew Brost <matthew.brost@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/20220121043118.24886-4-matthew.brost@intel.com