drm/i915/mtl: Apply notify_guc to all GTs

Handle platforms with multiple GTs by iterate over all GTs.
Add a Fixes commit so this gets propagated for MTL support.

Fixes: 213c4367 ("drm/i915/mtl: Remove the 'force_probe' requirement for Meteor Lake")
Suggested-by: John Harrison <john.c.harrison@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Andi Shyti <andi.shyti@linux.intel.com>
Cc: Andrzej Hajda <andrzej.hajda@intel.com>
Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231025102826.16955-1-nirmoy.das@intel.com
(cherry picked from commit 949113d3)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/i915_debugfs_params.c

@@ -38,10 +38,13 @@ static int i915_param_int_open(struct inode *inode, struct file *file)
 
 static int notify_guc(struct drm_i915_private *i915)
 {
-	int ret = 0;
+	struct intel_gt *gt;
+	int i, ret = 0;
 
-	if (intel_uc_uses_guc_submission(&to_gt(i915)->uc))
-		ret = intel_guc_global_policies_update(&to_gt(i915)->uc.guc);
+	for_each_gt(gt, i915, i) {
+		if (intel_uc_uses_guc_submission(&gt->uc))
+			ret = intel_guc_global_policies_update(&gt->uc.guc);
+	}
 
 	return ret;
 }