usb: xhci: fsl: add new compatible fsl,ls1028a-dwc3

usb: xhci: fsl: add new compatible fsl,ls1028a-dwc3

The official ls1028a binding of the driver uses the following as
compatibles:
  compatible = "fsl,ls1028a-dwc3", "snps,dwc3";

Change the ls1028a device tree and add this new compatible to the fsl
specific xhci driver, otherwise the generic dwc3 driver will be used
with the compatibles above.

Cc: Bin Meng <bmeng.cn@gmail.com>
Cc: Marek Vasut <marex@denx.de>
Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>