ath9k: move hw code to its own module

hw code for Atheros 802.11n hardware is commmon between
different chipsets. This moves this code into a separate
module, the next expected user of this code will be
the ath9k_htc module.

The ath9k/ dir is now selected by ATH9K_HW, an option which
gets selected by either ath9k or ath9k_htc, but remains
invisible for user menuconfig configuration. If either
ath9k or ath9k_htc will be compiled into the kernel
ath9k_hw will also be compiled in.

Cc: Jouni Malinen <jouni.malinen@atheros.com>
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/Makefile b/drivers/net/wireless/ath/Makefile
index 5c8e6b2..8113a50 100644
--- a/drivers/net/wireless/ath/Makefile
+++ b/drivers/net/wireless/ath/Makefile
@@ -1,5 +1,5 @@
 obj-$(CONFIG_ATH5K)		+= ath5k/
-obj-$(CONFIG_ATH9K)		+= ath9k/
+obj-$(CONFIG_ATH9K_HW)		+= ath9k/
 obj-$(CONFIG_AR9170_USB)        += ar9170/
 
 obj-$(CONFIG_ATH_COMMON)	+= ath.o