b43: LP-PHY: Implement channel switching for rev0/1/B2062 radio

-Move pdiv from lpphy_2062_init to struct b43_phy_lp.
-Add channel table for the B2062 radio.
-Add code for tuning the B2062 radio to channel.
-Add error handling to op_switch_channel, and use it for both radios.

Rev0/1/B2062 will now hopefully show some signs of life, though
it won't work at full performance, as calibration is still missing.

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