armv8: fsl-layerscape: identify boot source from PORSR register

PORSR register holds the cfg_rcw_src field which can be used
to identify boot source.

Further, it can be used to select the environment location.

Signed-off-by: Pankit Garg <pankit.garg@nxp.com>
Signed-off-by: Rajesh Bhagat <rajesh.bhagat@nxp.com>
[YS: fix multiple checkpatch issues]
Reviewed-by: York Sun <york.sun@nxp.com>
4 files changed