This adds basic support for the GPIOs in the twl4030 power management
chip.  That includes two open drain LED drivers, and the use of GPIO-0
(and GPIO-1) as MMC/SD card detect switches which can control whether
the VMMC1 (and VMMC2) regulators are active.

This version of the code has a debounce call that will probably be
replaced before long, when a more generic interface exists.
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: NTony Lindgren <tony@atomide.com>
Signed-off-by: NSamuel Ortiz <sameo@openedhand.com>