ARM: kirkwood: SBx81LIFKW: enable CMD_GPIO

For debugging it is convenient to query/access GPIOs from the command
line.

Signed-off-by: Chris Packham <judge.packham@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/configs/SBx81LIFKW_defconfig b/configs/SBx81LIFKW_defconfig
index 90800e2..ad7e2e9 100644
--- a/configs/SBx81LIFKW_defconfig
+++ b/configs/SBx81LIFKW_defconfig
@@ -26,6 +26,7 @@
 CONFIG_SYS_PBSIZE=276
 CONFIG_CMD_DM=y
 # CONFIG_CMD_FLASH is not set
+CONFIG_CMD_GPIO=y
 CONFIG_CMD_I2C=y
 CONFIG_CMD_DHCP=y
 CONFIG_BOOTP_NTPSERVER=y