arm64: dts: marvell: add NAND support on the 7040-DB board

arm64: dts: marvell: add NAND support on the 7040-DB board

The NAND controller used in A7K/A8K is present on the CP110 master part.
It is compatible with the pxa3xx_nand driver but requires the use of the
marvell,armada-8k-nand compatible string due to the need to first enable
the NAND controller.

Add properties to the NAND node to fit the bindings constraints of the
pxa3xx_nand driver and enable the NAND controller.

Add the 'marvell,system-controller' property to the cp110 master NAND
node with a reference to the syscon node. This is new compared to other
boards using the pxa3xx_nand driver and it is needed to be bootloader
independent and enable the NAND controller from the NAND controller
driver itself by writing in these syscon registers.

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
[miquel.raynal@free-electrons.com: add NAND ready/busy MPP subnode,
change compatible string to fit the needs of the A7k/A8k SoCs and add
the system controller property]
Signed-off-by: Miquel Raynal <miquel.raynal@free-electrons.com>