am33xx: pepper: Add Gumstix Pepper SBC

This add the Gumstix Pepper single-board computer based on the
TI AM335x processor. This is created as a separate board file
for development; not for upstream.
am335x: pepper: Add Pepper + Android defconfig

As per http://source.android.com/devices/tech/kernel.html,
Android likes some specific configurations.  These have been
merged where possible.  Several don't exist and CONFIG_USB_OTG_WAKELOCK
causes a build failure so these do not get set. In general, we don't
use modules for android builds.