doc: gpio-mvebu: fix broken reference to cp110-system-controller0.txt file

The cp110-system-controller0.txt file was renamed to
cp110-system-controller.txt.

Fixes: 4aa54969 ("dt-bindings: cp110: rename cp110 syscon file")
Signed-off-by: Otto Sabart <ottosabart@seberm.com>
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/gpio/gpio-mvebu.txt

@@ -14,8 +14,6 @@ Required properties:
 
     "marvell,armada-8k-gpio" should be used for the Armada 7K and 8K
     SoCs (either from AP or CP), see
-    Documentation/devicetree/bindings/arm/marvell/cp110-system-controller0.txt
-    and
     Documentation/devicetree/bindings/arm/marvell/ap806-system-controller.txt
     for specific details about the offset property.