drm/xe: fix error handling in xe_migrate_update_pgtables

Don't call drm_suballoc_free with sa_bo pointing to PTR_ERR.

References: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/2120
Fixes: dd08ebf6 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: <stable@vger.kernel.org> # v6.8+
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240620102025.127699-2-matthew.auld@intel.com

drivers/gpu/drm/xe/xe_migrate.c

@@ -1358,7 +1358,7 @@ xe_migrate_update_pgtables(struct xe_migrate *m,
 						 GFP_KERNEL, true, 0);
 			if (IS_ERR(sa_bo)) {
 				err = PTR_ERR(sa_bo);
-				goto err;
+				goto err_bb;
 			}
 
 			ppgtt_ofs = NUM_KERNEL_PDE +
@@ -1406,7 +1406,7 @@ xe_migrate_update_pgtables(struct xe_migrate *m,
 					 update_idx);
 	if (IS_ERR(job)) {
 		err = PTR_ERR(job);
-		goto err_bb;
+		goto err_sa;
 	}
 
 	/* Wait on BO move */
@@ -1458,10 +1458,10 @@ xe_migrate_update_pgtables(struct xe_migrate *m,
 
 err_job:
 	xe_sched_job_put(job);
+err_sa:
+	drm_suballoc_free(sa_bo, NULL);
 err_bb:
 	xe_bb_free(bb, NULL);
-err:
-	drm_suballoc_free(sa_bo, NULL);
 	return ERR_PTR(err);
 }