Add a routine to program the timing parameters for DDR3-1333 DRAM chips
connected to the H6 DRAM controller.

The values were gathered from doing back-calculations from a register
dump, trying to match them up with the official JEDEC DDDR3 spec.
If in doubt, the register dump values were taken for now, but the JEDEC
recommendation were added as a comment.

Many thanks to Jernej for contributing fixes!
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
Tested-by: NJernej Skrabec <jernej.skrabec@siol.net>
Reviewed-by: NJernej Skrabec <jernej.skrabec@siol.net>
Reviewed-by: NJagan Teki <jagan@amarulasolutions.com>