thermal: armada: Support Armada 380 SoC

Now that a generic infrastructure is in place, it's possible to support
the Armada 380 SoC thermal sensor. This sensor is similar to the one
available in the already supported SoCs, with its specific temperature formula
and specific sensor initialization.

Acked-by: Jason Cooper <jason@lakedaemon.net>
Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>