drm/xe: do not register to PM if GuC is disabled

When working without GuC (i.e. working with execlists), the flow
attempts to perform suspend operation which is failing due to a
lack of support without GuC.

If PM ops are not supported without GuC we may as well avoid PM
registration rather than returning errors from various PM flows.
Signed-off-by: Ohad Sharabi <osharabi@habana.ai>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/xe/xe_gt.c

@@ -641,10 +641,6 @@ int xe_gt_suspend(struct xe_gt *gt)
 {
 	int err;
 
-	/* For now suspend/resume is only allowed with GuC */
-	if (!xe_device_uc_enabled(gt_to_xe(gt)))
-		return -ENODEV;
-
 	xe_gt_sanitize(gt);
 
 	xe_device_mem_access_get(gt_to_xe(gt));

drivers/gpu/drm/xe/xe_pm.c

@@ -156,6 +156,10 @@ void xe_pm_init(struct xe_device *xe)
 {
 	struct pci_dev *pdev = to_pci_dev(xe->drm.dev);
 
+	/* For now suspend/resume is only allowed with GuC */
+	if (!xe_device_uc_enabled(xe))
+		return;
+
 	drmm_mutex_init(&xe->drm, &xe->d3cold.lock);
 
 	xe->d3cold.capable = xe_pm_pci_d3cold_capable(pdev);