arm64: dts: marvell: Add AP806-dual cache description

Adding appropriate entries to device-tree allows the cache description
to show up in sysfs under: /sys/devices/system/cpu/cpuX/cache/.

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