Allow User select Tablet Mode

Device overlay variables for tablet mode on Tuna.
Needs other Tablet UI commits.

Change-Id: I466ffa9dac9e5e553d37855f8e8d153fc583e5a0
Signed-off-by: Zaphod <mwilson@acesappraisal.com>
grouper: enable USB OTG storage

Change-Id: I0ffbd3f69895e7918cf61d505177bfd589fcdf8a
Enable rndis support for USB Tethering

Change-Id: Ib18112745553ec83849450f2ab2ee0cc3d4ef0ae