dt-bindings: ap806: prepare the syscon file to list other syscons nodes

There are multiple system controllers in AP806. Because all syscon nodes
use the same compatible, it is pertinent to use this same file to list
IPs inside it. Thus, change the header to be more generic.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>