ath: Copy key cache management functions from ath9k to ath

Copied the key cache management functions from ath9k (common.c and hw.c) to
ath/key.c so we can use them from ath5k, later.

Minor changes have been made:
 - renamed ath9k_* to ath_*
 - replaced ah->caps.keycache_size with common->keymax
 - removed ATH9K_IS_MIC_ENABLED since it is always true.
 - the AR_PCU_MIC_NEW_LOC_ENA flag is replaced with (splitmic == 0).

Signed-off-by: Bruno Randolf <br1@einfach.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/Makefile b/drivers/net/wireless/ath/Makefile
index 40fa179..6d711ec 100644
--- a/drivers/net/wireless/ath/Makefile
+++ b/drivers/net/wireless/ath/Makefile
@@ -7,6 +7,7 @@
 
 ath-objs :=	main.o \
 		regd.o \
-		hw.o
+		hw.o \
+		key.o
 
 ath-$(CONFIG_ATH_DEBUG) += debug.o