atheros: define shared bssidmask setting

Also make ath5k and ath9k use it, and share register definitions.

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
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 4a85f6c..d752b16 100644
--- a/drivers/net/wireless/ath/ath9k/main.c
+++ b/drivers/net/wireless/ath/ath9k/main.c
@@ -1570,6 +1570,7 @@
 
 	common = ath9k_hw_common(ah);
 	common->ops = &ath9k_common_ops;
+	common->ah = ah;
 
 	/*
 	 * Cache line size is used to size and align various