drm/xe/vf: Don't try to read legacy GuC MMIO notification if VF

Legacy SOFT_SCRATCH registers are not accessible from the VF. Any
G2H notification posted there will be handled by the PF driver.
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240405133936.891-4-michal.wajdeczko@intel.com

drivers/gpu/drm/xe/xe_guc.c

@@ -591,6 +591,9 @@ static void guc_handle_mmio_msg(struct xe_guc *guc)
 	struct xe_gt *gt = guc_to_gt(guc);
 	u32 msg;
 
+	if (IS_SRIOV_VF(guc_to_xe(guc)))
+		return;
+
 	xe_force_wake_assert_held(gt_to_fw(gt), XE_FW_GT);
 
 	msg = xe_mmio_read32(gt, SOFT_SCRATCH(15));