ath9k_hw: remove wrapper ath9k_hw_write_regs()

This is used only once by ath9k_hw_process_ini() to
write an array of phy registers through REG_WRITE_ARRAY(),
but we already call REG_WRITE_ARRAY() multiple times
on the same caller so just remove this pointless wrapper.
We'll eventually just move the ath9k_hw_process_ini()
caller as an callback to abstract away between different
hardware families.

Although this change is subtle I should note that this
does change the delay pattern on writing the next series
of registers. REG_WRITE_ARRAY() uses a counter for each
register write and does a udelay(1) every 64 writes. By
removing this call it means that the counter is processed
for all the iniBB_RfGain registers and is incremented
on ath9k_hw_process_ini(), before this the after the call
ath9k_hw_write_regs() was made the register counter was
kept at the same index number prior to the call.

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>