[PATCH u-boot-marvell] PLEASE TEST ddr: marvell: a38x: fix SPLIT_OUT_MIX state decision

[Marek Behun]

This patch is needed on some Turris Omnia boards with Samsung DDR chips,
otherwise DDR training fails in ~60% of cases.

Marvell send us this patch for testing, I have updated it a little.

Please test this on other A38x boards.

If it doesn't break anything on other boards, we can apply it and send
it to mv-ddr-marvell upstream.

Marek