drm/xe: fix typo "notifer"

There is a spelling mistake of 'notifer' in the comment which
should be 'notifier'.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: WangYuli <[email protected]>
Reviewed-by: Thomas Hellström <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: WangYuli

drivers/gpu/drm/xe/xe_vm_types.h

@@ -259,7 +259,7 @@ struct xe_vm {
 		 * up for revalidation. Protected from access with the
 		 * @invalidated_lock. Removing items from the list
 		 * additionally requires @lock in write mode, and adding
-		 * items to the list requires either the @userptr.notifer_lock in
+		 * items to the list requires either the @userptr.notifier_lock in
 		 * write mode, OR @lock in write mode.
 		 */
 		struct list_head invalidated;