arm64: dts: layerscape: add platform special compatible string for gpio

arm64: dts: layerscape: add platform special compatible string for gpio

Add platform special compatible string for all gpio controller to fix
below warning.

 gpio@2300000: compatible: 'oneOf' conditional failed, one must be fixed:
        ['fsl,qoriq-gpio'] is too short
        'fsl,qoriq-gpio' is not one of ['fsl,mpc5121-gpio', 'fsl,mpc5125-gpio', 'fsl,mpc8349-gpio', 'fsl,mpc8572-gpio', 'fsl,mpc8610-gpio', 'fsl,pq3-gpio']
        'fsl,qoriq-gpio' is not one of ['fsl,ls1021a-gpio', 'fsl,ls1028a-gpio', 'fsl,ls1043a-gpio', 'fsl,ls1088a-gpio', 'fsl,ls2080a-gpio']

Signed-off-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>