dt-bindings: gpio: mrvl-gpio: Fix the gpio-ranges property

The property specifies a list of GPIO-capable pins. Don't limit it to a
single element as there's presumably more than one GPIO pin.

Signed-off-by: Lubomir Rintel <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]'
Signed-off-by: Arnd Bergmann <[e-mail]>

Documentation/devicetree/bindings/gpio/mrvl-gpio.yaml

···
   '#gpio-cells':
     const: 2
 
-  gpio-ranges:
-    maxItems: 1
+  gpio-ranges: true
 
   interrupts: true