b43: LP-PHY: Fix a few typos in the RC calibration code

The RC calibration code has some typos - fix them.
Also, make the default channel 7, as channel 1 is still
broken (only channels 7 and 8, and occasionally 9 work).

Signed-off-by: Gábor Stefanik <netrolller.3d@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>