drm/i915: Allocate intel_engine_coredump_alloc with ALLOW_FAIL

Allocate intel_engine_coredump_alloc with ALLOW_FAIL rather than
GFP_KERNEL to fully decouple the error capture from fence signalling.

v2:
 (John Harrison)
  - Fix typo in commit message (s/do/to)

Fixes: 8b91cdd4 ("drm/i915: Use __GFP_KSWAPD_RECLAIM in the capture code")
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/20220121043118.24886-2-matthew.brost@intel.com
(cherry picked from commit 4f72fc3c)
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

drivers/gpu/drm/i915/i915_gpu_error.c

@@ -1522,7 +1522,7 @@ capture_engine(struct intel_engine_cs *engine,
 	struct i915_request *rq = NULL;
 	unsigned long flags;
 
-	ee = intel_engine_coredump_alloc(engine, GFP_KERNEL);
+	ee = intel_engine_coredump_alloc(engine, ALLOW_FAIL);
 	if (!ee)
 		return NULL;