drm/i915/execlists: Avoid sync calls during park

Since we allow ourselves to use non-process context during parking, we
cannot allow ourselves to sleep and in particular cannot call
del_timer_sync() -- but we can use a plain del_timer().

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111375
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190812091045.29587-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/gt/intel_lrc.c

@@ -2728,7 +2728,7 @@ static u32 *gen8_emit_fini_breadcrumb_rcs(struct i915_request *request, u32 *cs)
 
 static void execlists_park(struct intel_engine_cs *engine)
 {
-	del_timer_sync(&engine->execlists.timer);
+	del_timer(&engine->execlists.timer);
 }
 
 void intel_execlists_set_default_submission(struct intel_engine_cs *engine)