arm64: dts: marvell: Enumerate the first AP806 syscon

There are two system controllers in the AP80x, like for ap_syscon1,
enumerate the first one by renaming it s/ap_syscon/ap_syscon0/.

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