b43: N-PHY: implement reading support for radio 0x2057

Bit 0x200 has been noticed in the following log:
 radio_read(0x02ca) -> 0x0000
radio_write(0x00ca) <- 0x0080
Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/b43/phy_n.c

@@ -5522,7 +5522,10 @@ static u16 b43_nphy_op_radio_read(struct b43_wldev *dev, u16 reg)
 {
 	/* Register 1 is a 32-bit register. */
 	B43_WARN_ON(reg == 1);
-	/* N-PHY needs 0x100 for read access */
+
+	if (dev->phy.rev >= 7)
+		reg |= 0x200; /* Radio 0x2057 */
+	else
 		reg |= 0x100;
 
 	b43_write16(dev, B43_MMIO_RADIO_CONTROL, reg);