rt2x00: Don't disable G0 PA_PE bit in case of BT coexistence.

(split off from the earlier RT35xx patch submitted by Shiang)

Signed-off-by: Shiang Tu <shiang_tu@ralinktech.com>
Signed-off-by: Gertjan van Wingerde <gwingerde@gmail.com>
Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>