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/SBx81LIFKW_defconfig b/configs/SBx81LIFKW_defconfig
index ec7c7eb..77f44f6 100644
--- a/configs/SBx81LIFKW_defconfig
+++ b/configs/SBx81LIFKW_defconfig
@@ -35,6 +35,7 @@
 CONFIG_SYS_RELOC_GD_ENV_ADDR=y
 CONFIG_NETCONSOLE=y
 CONFIG_DM=y
+CONFIG_KIRKWOOD_GPIO=y
 CONFIG_DM_PCA953X=y
 CONFIG_DM_I2C=y
 CONFIG_SYS_I2C_MVTWSI=y