Update bbp register initialization for RT53xx chips to match with the
latest MediaTek/Ralink driver.

Based on: NICInitRT5390BbpRegisters()
From: DPO_RT5572_LinuxSTA_2.6.1.3_20121022/chips/rt5390.c

Signed-off-by: Kevin Lo <kevlo.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>