Convert CONFIG_TWL4030_LED et al to Kconfig

This converts the following to Kconfig:
   CONFIG_TWL4030_LED
   CONFIG_TWL4030_INPUT

This also removes dead references to:
   CONFIG_TWL4030_KEYPAD

Signed-off-by: Adam Ford <aford173@gmail.com>
diff --git a/configs/omap3_overo_defconfig b/configs/omap3_overo_defconfig
index 8b4146d..0c4a021 100644
--- a/configs/omap3_overo_defconfig
+++ b/configs/omap3_overo_defconfig
@@ -31,6 +31,7 @@
 CONFIG_MTDPARTS_DEFAULT="mtdparts=omap2-nand.0:512k(xloader),1792k(u-boot),256k(environ),8m(linux),-(rootfs)"
 CONFIG_CMD_UBI=y
 CONFIG_ENV_IS_IN_NAND=y
+CONFIG_TWL4030_LED=y
 CONFIG_MMC_OMAP_HS=y
 CONFIG_NAND=y
 CONFIG_SYS_NAND_BUSWIDTH_16BIT=y