arm64: dts: marvell: Add UART1-3 for AC5/AC5X

The AC5/AC5X SoC has 4 UART blocks. Add the additional UART1-3 blocks to
the base dtsi file.

Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>