drm/xe/xe_exec : In xe_exec_ioctl remove deadcode

At label err_unlock_list the condition write_label will never be true.
Remove the deadcode line for write_label true.

Reported by static analyzer.

Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Tejas Upadhyay <tejas.upadhyay@intel.com>
Cc: Bommu Krishnaiah <krishnaiah.bommu@intel.com>
Reviewed-by: Tejas Upadhyay <tejas.upadhyay@intel.com>
Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240313150545.2830408-3-himal.prasad.ghimiray@intel.comSigned-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/xe/xe_exec.c

@@ -380,10 +380,7 @@ int xe_exec_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
 err_exec:
 	drm_exec_fini(exec);
 err_unlock_list:
-	if (write_locked)
-		up_write(&vm->lock);
-	else
-		up_read(&vm->lock);
+	up_read(&vm->lock);
 	if (err == -EAGAIN && !skip_retry)
 		goto retry;
 err_syncs: