usb: host: xhci-plat: Use of_device_get_match_data() helper

Use the of_device_get_match_data() helper instead of open coding.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>