ARM: mvebu: a38x: restore support for setting timing

This restores support for configuring the timing mode based on the
ddr_topology. This was originally implemented in commit 90bcc3d3
("driver/ddr: Add support for setting timing in hws_topology_map") but
was removed as part of the upstream sync.

Signed-off-by: Chris Packham <judge.packham@gmail.com>
Signed-off-by: Stefan Roese <sr@denx.de>