dt: Update binding information for mvebu gating clocks with Armada 380/385

Add the binding information for the gating clocks of the Armada 380
SoCs and the Armada 385 SoCs.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>