b43: HT-PHY: init: add missing PHY mask/set ops

MMIO hacks were used to trick ndis&wl. For example following:
 phy_read(0x0280) -> 0xffff
phy_write(0x0280) <- 0xff3e
***
 phy_read(0x0280) -> 0x0000
phy_write(0x0280) <- 0x003e
was translated to mask 0xff00 and set 0x3e.

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