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/drivers/input/Kconfig b/drivers/input/Kconfig
index b3873c1..7ffb949 100644
--- a/drivers/input/Kconfig
+++ b/drivers/input/Kconfig
@@ -24,3 +24,8 @@
 	  driver handles English and German keyboards - set the environment
 	  variable 'keymap' to "de" to select German. Keyboard repeat is
 	  handled by the keyboard itself.
+
+config TWL4030_INPUT
+	bool "Enable TWL4030 Input controller"
+	help
+	  Enable TWL4030 Input controller