dt-bindings: thermal: Describe Armada AP806 and CP110

Add compatible strings for AP806 and CP110 that are part of the Armada
8k/7k line of SoCs.

Add a note on the differences in the size of the control area in
different bindings. This is an existing difference between the Armada
375 binding and the other boards already supported. The new AP806 and
CP110 bindings are similar to the existing Armada 375 in this regard.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
[<miquel.raynal@free-electrons.com>: reword, additional details]
Signed-off-by: Miquel Raynal <miquel.raynal@free-electrons.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>