dt-bindings: cp110: rename cp110 syscon file

There is no need to give numbers to system controllers inside the
documentation as the syscons use the same compatibles. Furthermore, this
approach does not scale very well and would force the creation of a new
file each time a new syscon is added in the device tree.
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>