arm64: dts: marvell: clearfog-gt-8k: add cooling maps

Add cooling maps suitable for a Noctua NF-A4/10 fan attached to the
heat sink.  The fan will toggle between two speeds in operation which
seems to be normal behaviour.  More fine-grained steps may help to
reduce this.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>