ath5k: free sc->ah in ath5k_deinit_softc

Nothing else is freeing it, and this mirrors the error handling path
already in ath5k_init_softc.

https://bugzilla.kernel.org/show_bug.cgi?id=37592

Signed-off-by: John W. Linville <linville@tuxdriver.com>
Reported-by: Tsyvarev Andrey <tsyvarev@ispras.ru>

drivers/net/wireless/ath/ath5k/base.c

@@ -2960,6 +2960,7 @@ ath5k_deinit_softc(struct ath5k_softc *sc)
 	 * state and potentially want to use them.
 	 */
 	ath5k_hw_deinit(sc->ah);
+	kfree(sc->ah);
 	free_irq(sc->irq, sc);
 }