arm: mx6: Add Barco platinum-picon and platinum-titanium

arm: mx6: Add Barco platinum-picon and platinum-titanium

This patch adds the new Barco platinum platform. It currently
includes those two boards:

platinum-titanium
-----------------
This is the same board as the titanium that is already supported in
mainline U-Boot. But its now moved to this new platform to support
multiple "flavors" of imx6 boards in one directory. Its also moved
to support SPL booting. And with this we use the run-time DDR
configuration of this SPL support. The board is equipped with the
Micron MT41J128M16JT-125 DDR chips. We now can remove the DDR
related registers tuples from the imximage.cfg file. As all this
is done in the SPL at run-time.

platinum-picon
--------------
This board is new and based on the MX6DL with 1GiB DDR using the
Micron MT41K256M16HA DDR3 chips. Its also equipped with 2 NAND
chips (each 512MiB).

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Pieter Ronsijn <pieter.ronsijn@barco.com>