arm64: dts: marvell: use mvebu-icu.h where possible

Back when the ICU Device Tree binding was introduced, we could not use
mvebu-icu.h from the Device Tree files, because the DT files and
mvebu-icu.h were following different merge routes towards Linus
tree. Now that both have been merged, we can switch the Marvell Armada
CP110 Device Tree files to use the mvebu-icu.h header instead of
duplicating the ICU_GRP_NSR definition.

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