Add support for the MPC8349E-mITX-GP, a stripped-down version of the
MPC8349E-mITX.  Bonus features include support for low-boot (BMS bit in
HRCW is 0) for the ITX and a README for the ITX and the ITX-GP.

Signed-off-by: Timur Tabi <timur@freescale.com>