drm/xe: Allow the pm notifier to continue on failure

Its actions are opportunistic anyway and will be completed
on device suspend.

Marking as a fix to simplify backporting of the fix
that follows in the series.

v2:
- Keep the runtime pm reference over suspend / hibernate and
  document why. (Matt Auld, Rodrigo Vivi):

Fixes: c6a4d46 ("drm/xe: evict user memory in PM notifier")
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: <stable@vger.kernel.org> # v6.16+
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://lore.kernel.org/r/20250904160715.2613-3-thomas.hellstrom@linux.intel.com
(cherry picked from commit ebd546f)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

Author: Thomas Hellström

drivers/gpu/drm/xe/xe_pm.c

@@ -301,17 +301,17 @@ static int xe_pm_notifier_callback(struct notifier_block *nb,
 	case PM_SUSPEND_PREPARE:
 		xe_pm_runtime_get(xe);
 		err = xe_bo_evict_all_user(xe);
-		if (err) {
+		if (err)
 			drm_dbg(&xe->drm, "Notifier evict user failed (%d)\n", err);
-			xe_pm_runtime_put(xe);
-			break;
-		}
 
 		err = xe_bo_notifier_prepare_all_pinned(xe);
-		if (err) {
+		if (err)
 			drm_dbg(&xe->drm, "Notifier prepare pin failed (%d)\n", err);
-			xe_pm_runtime_put(xe);
-		}
+		/*
+		 * Keep the runtime pm reference until post hibernation / post suspend to
+		 * avoid a runtime suspend interfering with evicted objects or backup
+		 * allocations.
+		 */
 		break;
 	case PM_POST_HIBERNATION:
 	case PM_POST_SUSPEND:
@@ -320,9 +320,6 @@ static int xe_pm_notifier_callback(struct notifier_block *nb,
 		break;
 	}
 
-	if (err)
-		return NOTIFY_BAD;
-
 	return NOTIFY_DONE;
 }