drbd: fix typo in comment

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

drivers/block/drbd/drbd_actlog.c

@@ -546,7 +546,7 @@ cancel:
 }
 
 /**
- * drbd_al_apply_to_bm() - Sets the bitmap to diry(1) where covered ba active AL extents
+ * drbd_al_apply_to_bm() - Sets the bitmap to dirty(1) where covered by active AL extents
  * @mdev:	DRBD device.
  */
 void drbd_al_apply_to_bm(struct drbd_conf *mdev)