ath9k_hw: Fix incorrect baseband PLL phase shift for AR9485

we should program the AR9485 baseband PLL phase shift to 6 and
a redundant setting overwrites the correct value. Remove the
incorrect and unwnated register setting.

Signed-off-by: Senthil Balasubramanian <senthilkumar@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>