ddr: marvell: a38x: disable WL phase correction stage in case of bus_width=16bit

commit 20c89a28548cdab11f88d2ec8936344af0686a1e upstream.

WL phase correcion stage is failing while using bus_width of 16bit, not
to be fix this stage is un-necessary when working with bus_width of 16
bit.

Signed-off-by: Moti Buskila <motib@marvell.com>
Reviewed-by: Kostya Porotchkin <kostap@marvell.com>
Signed-off-by: Marek Behún <marek.behun@nic.cz>
Tested-by: Chris Packham <chris.packham@alliedtelesis.co.nz>