dt-bindings: gpio: fsl,qoriq-gpio: add common property gpio-line-names

Add common gpio-line-names property for fsl,qoriq-gpio to fix below
warning.

arch/arm64/boot/dts/freescale/fsl-ls1028a-kontron-kbox-a-230-ls.dtb: gpio@2300000: 'gpio-line-names' does not match any of the regexes: 'pinctrl-[0-9]+'
from schema $id: http://devicetree.org/schemas/gpio/fsl,qoriq-gpio.yaml

Signed-off-by: Frank Li <[e-mail]>
Acked-by: Krzysztof Kozlowski <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Bartosz Golaszewski <[e-mail]>

Documentation/devicetree/bindings/gpio/fsl,qoriq-gpio.yaml

···
   "#interrupt-cells":
     const: 2
 
+  gpio-line-names:
+    minItems: 1
+    maxItems: 32
+
   little-endian:
     $ref: /schemas/types.yaml#/definitions/flag
     description: