dt: Update binding information for mvebu core clocks with Armada 375

Add the binding information for the core clocks of the Armada 375 SoCs

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