ARM: mvebu: correct a385-db-ap compatible string

This commit enables standby support on Armada 385 DB-AP board, because
the PM initalization routine requires "marvell,armada380" compatible
string for all Armada 38x-based platforms.

Beside the compatible "marvell,armada38x" was wrong and should be fixed
in the stable kernels too.

[gregory.clement@free-electrons.com: add information, about the fixes]
Fixes: e5ee1281 ("ARM: mvebu: Add Armada 385 Access Point
Development Board support")
Signed-off-by: Marcin Wojtas <mw@semihalf.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Cc: <stable@vger.kernel.org>