rt2800: fix RT5390 & RT3290 TX power settings regression

rt2800: fix RT5390 & RT3290 TX power settings regression

My change:

commit 91b1c7a28ece8b961cadb1039eccd71e418b461b
Author: Stanislaw Gruszka <sgruszka@redhat.com>
Date:   Fri Oct 5 13:44:09 2012 +0200

    rt2800: use BBP_R1 for setting tx power

unfortunately does not work well with RT5390 and RT3290 chips as they
require different temperature compensation TX power settings (TSSI
tuning). Since that commit make wireless connection very unstable on
those chips, restore previous behavior to fix regression. Once we
implement proper TSSI tuning on 5390/3290 we can restore back setting
TX power by BBP_R1 register for those chips.

Reported-and-tested-by: Mike Romberg <mike-romberg@comcast.net>
Cc: stable@vger.kernel.org
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Acked-by: Gertjan van Wingerde <gwingerde@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>