ARM: dts: imx: fix the schema check errors

- ranges property should be grouped by region, with no functional
  changes. Otherwise, schema dtbs_check would report the following errors.
"linux-imx/arch/arm/boot/dts/imx6qp-vicutp.dt.yaml: pcie@1ffc000: ranges: 'oneOf' conditional failed, one must be fixed:
        linux-imx/arch/arm/boot/dts/imx6qp-vicutp.dt.yaml: pcie@1ffc000: ranges: 'oneOf' conditional failed, one must be fixed:
                [[2164260864, 0, 0, 33030144, 0, 65536, 2181038080, 0, 16777216, 16777216, 0, 15728640]] is not of type 'boolean'
                True was expected
                [[2164260864, 0, 0, 33030144, 0, 65536, 2181038080, 0, 16777216, 16777216, 0, 15728640]] is not of type 'null'
        [2164260864, 0, 0, 33030144, 0, 65536, 2181038080, 0, 16777216, 16777216, 0, 15728640] is too long
        From schema: linux-imx/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.yaml"
- refer to commit 281f1f99 ("PCI: dwc: Detect number of iATU windows").
  The num-viewport is not required anymore, remove them totally.
- dt_binding_check complains "compatible: ['fsl,imx6qp-pcie', 'snps,dw-pcie']
  is too long", remove "snps,dw-pcie" from the compatible string.

Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>