ARM: kirkwood: SBx81LIFKW: disable KIRKWOOD_GPIO

DM_GPIO was already enabled so the MVEBU_GPIO was already available.
Having updated the board code to use the DM_GPIO APIs the KIRKWOOD_GPIO
driver became unnecessary. Disable it for SBx81LIFKW.

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 ad7e2e9..ec940bd 100644
--- a/configs/SBx81LIFKW_defconfig
+++ b/configs/SBx81LIFKW_defconfig
@@ -41,7 +41,6 @@
 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