mogami-common: switch to a cleaner two-stage boot method

this let's us have two separate real ramdisks which is more cleaner than having
a combined ramdisk.

on boot there will be decided which one of the ramdisks (android or recovery) gets unpacked and fired up.

Ported from: http://review.cyanogenmod.org/#/c/26441/
Author: codeworkx <codeworkx@cyanogenmod.com>
Signed-off-by: Michael Bestas <mikeioannina@gmail.com>

Change-Id: I9c0a7e484d063e3e020fdc032472f5541a9015d6