b43: LCN-PHY: switch analog

Analog is switched on right after reading PHY version:
 read16 0xfaafc3e0 -> 0xa801
 phy_read(0x043b) -> 0x0000
phy_write(0x043b) <- 0x0000
Switched off after after killing radio:
>>> Switch Radio(OFF) end
 phy_read(0x043c) -> 0x0000
phy_write(0x043c) <- 0x0007
 phy_read(0x043b) -> 0x0000
phy_write(0x043b) <- 0x0007

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>