ath9k: fix keycache leak in split tkip case

If split tkip key is used, ath_delete_key should delete
rx key and rx mic key. This patch fixes the leak of hw
keycache in the case.

Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/main.c b/drivers/net/wireless/ath/ath9k/main.c
index 40da7a6..9c8f925 100644
--- a/drivers/net/wireless/ath/ath9k/main.c
+++ b/drivers/net/wireless/ath/ath9k/main.c
@@ -809,6 +809,7 @@
 
 	clear_bit(key->hw_key_idx + 64, common->keymap);
 	if (common->splitmic) {
+		ath9k_hw_keyreset(ah, key->hw_key_idx + 32);
 		clear_bit(key->hw_key_idx + 32, common->keymap);
 		clear_bit(key->hw_key_idx + 64 + 32, common->keymap);
 	}