dt-bindings: ap80x: Document AP807 CPU clock compatible

Add AP807 CPU clock compatible to the bindings.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lkml.kernel.org/r/20190805100310.29048-2-miquel.raynal@bootlin.com


Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>