ath9k_hw: simplify rf attach and rename to ath9k_hw_rf_alloc_ext_banks()

ath9k_hw_rfattach() was just calling a helper and this helper was
doing nothing for single-chip devices, and for non single-chip devices
it is just allocating memory for banks to program the RF registers
at a later time. Simplify this by having the hw initialization call
the rf bank allocation directly for external radios.

Also, propagate an -ENOMEM properly now upon failure.

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/phy.h b/drivers/net/wireless/ath/ath9k/phy.h
index b64bc69..0bbbfbc 100644
--- a/drivers/net/wireless/ath/ath9k/phy.h
+++ b/drivers/net/wireless/ath/ath9k/phy.h
@@ -29,8 +29,7 @@
 			  u16 modesIndex);
 void ath9k_hw_decrease_chain_power(struct ath_hw *ah,
 				   struct ath9k_channel *chan);
-bool ath9k_hw_init_rf(struct ath_hw *ah,
-		      int *status);
+int ath9k_hw_rf_alloc_ext_banks(struct ath_hw *ah);
 
 #define AR_PHY_BASE     0x9800
 #define AR_PHY(_n)      (AR_PHY_BASE + ((_n)<<2))