ath9k_hw: Optimize ath9k_hw_ar9287_set_board_values

Rather than doing a series of RMWs, calculate the
value to be written to the register in question and
do a single REGWRITE. This improves bringup time.

This depends on the analog_shiftreg configuration option,
which is currently buggy. For AP mode, a delay of 100us
has to be the default. For station mode, this knob has to
be enabled on a per-case basis, though it is a little
unclear on when to enable a delay. This can be fixed later though.

Signed-off-by: Sujith <Sujith.Manoharan@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/eeprom.h

@@ -679,6 +679,7 @@ struct eeprom_ops {
 	u16 (*get_spur_channel)(struct ath_hw *ah, u16 i, bool is2GHz);
 };
 
+void ath9k_hw_analog_shift_regwrite(struct ath_hw *ah, u32 reg, u32 val);
 void ath9k_hw_analog_shift_rmw(struct ath_hw *ah, u32 reg, u32 mask,
 			       u32 shift, u32 val);
 int16_t ath9k_hw_interpolate(u16 target, u16 srcLeft, u16 srcRight,