uboot-imx

sniper: Keypad support, with recovery and fastboot key combinations

Using the twl4030 keypad allows booting directly into some special boot modes,
such as recovery or fastboot. the VOL+ key will trigger a boot to recovery while
the VOL- key will trigger a boot to fastboot.

The G (gesture) key remains unused at this point.

Signed-off-by: Paul Kocialkowski <contact@paulk.fr>
Reviewed-by: Tom Rini <trini@konsulko.com>