Convert CONFIG_KIRKWOOD_GPIO to Kconfig

This converts the following to Kconfig:
   CONFIG_KIRKWOOD_GPIO

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/net2big_v2_defconfig b/configs/net2big_v2_defconfig
index ed60c48..985f530 100644
--- a/configs/net2big_v2_defconfig
+++ b/configs/net2big_v2_defconfig
@@ -48,6 +48,7 @@
 CONFIG_NETCONSOLE=y
 CONFIG_DM=y
 CONFIG_SATA_MV=y
+CONFIG_KIRKWOOD_GPIO=y
 CONFIG_SYS_I2C_LEGACY=y
 CONFIG_SYS_I2C_MVTWSI=y
 CONFIG_SYS_I2C_SLAVE=0x0