ddr: marvell: a38x: allow board specific ODT configuration

commit 2d3b9437cf38c06c4330e0de07f29476197f5e04 upstream.

The ODT enable heuristic based on active chip-selects is not always
correct. Some board might use two chip-selects, but have only one ODT
line connected. Allow board specific mv_ddr_topology_map to directly set
the ODT configuration register value.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Reviewed-by: Moti Buskila <motib@marvell.com>
Reviewed-by: Nadav Haklai <Nadav.Haklai@cavium.com>
Reviewed-by: Kostya Porotchkin <Kostya.Porotchkin@cavium.com>
Signed-off-by: Marek Behún <marek.behun@nic.cz>
Tested-by: Chris Packham <chris.packham@alliedtelesis.co.nz>