ARM: kirkwood: SBx81LIFKW: remove direct access of GPIO registers

Replace code that accessed the GPIO registers directly with code that
makes use of the LED_GPIO driver.

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 f186f24..90800e2 100644
--- a/configs/SBx81LIFKW_defconfig
+++ b/configs/SBx81LIFKW_defconfig
@@ -46,6 +46,8 @@
 CONFIG_SYS_I2C_MVTWSI=y
 CONFIG_I2C_MUX=y
 CONFIG_I2C_MUX_PCA954x=y
+CONFIG_LED=y
+CONFIG_LED_GPIO=y
 # CONFIG_MMC is not set
 CONFIG_MTD=y
 CONFIG_DM_SPI_FLASH=y