ath9k: add external_reset callback to ath9k_platfom_data for AR9330

The patch adds a callback to ath9k_platform_data. If the
callback is provided by the platform code, then it can be
used to hard reset the WMAC device.

The callback is required for doing a hard reset of the AR9330
chips to get them working again after a hang.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/init.c b/drivers/net/wireless/ath/ath9k/init.c
index 1851c22..50103b2 100644
--- a/drivers/net/wireless/ath/ath9k/init.c
+++ b/drivers/net/wireless/ath/ath9k/init.c
@@ -575,6 +575,7 @@
 		sc->sc_ah->led_pin = pdata->led_pin;
 		ah->is_clk_25mhz = pdata->is_clk_25mhz;
 		ah->get_mac_revision = pdata->get_mac_revision;
+		ah->external_reset = pdata->external_reset;
 	}
 
 	common = ath9k_hw_common(ah);