drm/xe/dg1: Fix power gate sequence.

sub-pipe PG is not present on DG1. Setting these bits can disable
other power gates and cause GPU hangs on video playbacks.

VLK: 16314, 4304

Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/13381
Cc: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
Cc: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241219235536.454270-1-rodrigo.vivi@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/xe/xe_gt_idle.c

@@ -122,10 +122,12 @@ void xe_gt_idle_enable_pg(struct xe_gt *gt)
 	if (!xe_gt_is_media_type(gt))
 		gtidle->powergate_enable |= RENDER_POWERGATE_ENABLE;
 
-	for (i = XE_HW_ENGINE_VCS0, j = 0; i <= XE_HW_ENGINE_VCS7; ++i, ++j) {
-		if ((gt->info.engine_mask & BIT(i)))
-			gtidle->powergate_enable |= (VDN_HCP_POWERGATE_ENABLE(j) |
-						     VDN_MFXVDENC_POWERGATE_ENABLE(j));
+	if (xe->info.platform != XE_DG1) {
+		for (i = XE_HW_ENGINE_VCS0, j = 0; i <= XE_HW_ENGINE_VCS7; ++i, ++j) {
+			if ((gt->info.engine_mask & BIT(i)))
+				gtidle->powergate_enable |= (VDN_HCP_POWERGATE_ENABLE(j) |
+							     VDN_MFXVDENC_POWERGATE_ENABLE(j));
+		}
 	}
 
 	fw_ref = xe_force_wake_get(gt_to_fw(gt), XE_FW_GT);