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/dns325_defconfig b/configs/dns325_defconfig
index c1da0f5..144fd30 100644
--- a/configs/dns325_defconfig
+++ b/configs/dns325_defconfig
@@ -41,6 +41,7 @@
 CONFIG_ENV_IS_IN_NAND=y
 CONFIG_NETCONSOLE=y
 CONFIG_DM=y
+CONFIG_KIRKWOOD_GPIO=y
 # CONFIG_MMC is not set
 CONFIG_MTD=y
 CONFIG_MTD_RAW_NAND=y