b43 G-PHY: Remove mmiowb()

It causes compile errors on m68k and it is not needed.
Remove it.
Signed-off-by: Michael Buesch <mb@bu3sch.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/b43/phy_g.c

@@ -386,7 +386,6 @@ static void b43_set_original_gains(struct b43_wldev *dev)
 void b43_nrssi_hw_write(struct b43_wldev *dev, u16 offset, s16 val)
 {
 	b43_phy_write(dev, B43_PHY_NRSSILT_CTRL, offset);
-	mmiowb();
 	b43_phy_write(dev, B43_PHY_NRSSILT_DATA, (u16) val);
 }