arm64: dts: marvell: use lower case for unit address and reg property

This fixes the following DTC warning:

  <stdout>: Warning (simple_bus_reg): Node /ap806/config-space@f0000000/thermal@6f808C simple-bus unit address format error, expected "6f808c"

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>