b43: disable 5 GHz on G-PHY

This fixes regression introduced by adding some G-PHY devices to the
list of dual band devices. There is simply no support for 5 GHz on
G-PHY devices in b43. It results in:
WARNING: CPU: 0 PID: 79 at drivers/net/wireless/b43/phy_g.c:75 b43_gphy_channel_switch+0x125/0x130 [b43]()
b43-phy1 ERROR: PHY init: Channel switch to default failed

Regression was introduced by the following commit:

commit 773cfc50
Author: Rafał Miłecki <zajec5@gmail.com>
Date:   Mon May 19 23:18:55 2014 +0200

    b43: add more devices to the bands database
Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/b43/main.c

@@ -5221,6 +5221,7 @@ static int b43_wireless_core_attach(struct b43_wldev *dev)
 	/* We don't support 5 GHz on some PHYs yet */
 	switch (dev->phy.type) {
 	case B43_PHYTYPE_A:
+	case B43_PHYTYPE_G:
 	case B43_PHYTYPE_N:
 	case B43_PHYTYPE_LP:
 	case B43_PHYTYPE_HT: