mb/intel/dg43gt: Enable the GBE

This was blindly copied from logs created under vendor BIOS in non-descriptor
mode which apparently set LAND in BUC.

Change-Id: I94c917600421ee742ece7f6f71309da80261da28
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/28048
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>

src/mainboard/intel/dg43gt/romstage.c

@@ -49,7 +49,7 @@ static void mb_gpio_init(void)
 	RCBA8(0x31ff);
 
 	RCBA32(0x3410) = 0x00060464;
-	RCBA32(0x3414) = 0x00000020;
+	RCBA32(RCBA_BUC) &= ~BUC_LAND;
 	RCBA32(0x3418) = 0x01320001;
 	RCBA32(0x341c) = 0xbf7f001f;
 	RCBA32(0x3430) = 0x00000002;