ARM: dts: armada-370-xp: update NAND node with new bindings

Use the new bindings of the Marvell NAND controller driver. Also adapt
the NAND controller node organization to distinguish which property is
relevant for the controller, and which one is NAND chip specific. Expose
the partitions as a subnode of the NAND chip.

Remove the 'marvell,nand-enable-arbiter' property, not needed anymore
as the new driver activates the arbiter by default for all boards which
is either needed or harmless.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>