ARM: Kirkwood: Add configuration for MPP12 as GPIO

The MPP12 is listed in the 6281 HW manual as output only but the iconnect
board from iomega is using it as GPIO (there's a button connected on it). So,
I'm adding a definition for the MPP12 as GPIO. As I've no informations about
this and which kirkwood are "affected", I'm adding a new #define instead of
modifying the current one for MPP12.
Signed-off-by: NArnaud Patard <arnaud.patard@rtp-net.org>
Signed-off-by: NNicolas Pitre <nico@fluxnic.net>

arch/arm/mach-kirkwood/mpp.h

@@ -102,6 +102,7 @@
 #define MPP11_SATA0_ACTn	MPP( 11, 0x5, 0, 1, 0,   1,   1,   1,   1 )
 
 #define MPP12_GPO		MPP( 12, 0x0, 0, 1, 1,   1,   1,   1,   1 )
+#define MPP12_GPIO		MPP( 12, 0x0, 1, 1, 0,   0,   0,   1,   0 )
 #define MPP12_SD_CLK		MPP( 12, 0x1, 0, 1, 1,   1,   1,   1,   1 )
 #define MPP12_AU_SPDIF0		MPP( 12, 0xa, 0, 1, 0,   0,   0,   0,   1 )
 #define MPP12_SPI_MOSI		MPP( 12, 0xb, 0, 1, 0,   0,   0,   0,   1 )