[PATCH] rt2x00: SW diversity should default to antenna B

Although ANTENNA_SW_DIVERSITY should never be send
to the driver, we should still handle it to prevent bugs.
But instead of defaulting to ANTENNA_HW_DIVERSITY we
should default to ANTENNA_B instead.

Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>