usb: dwc3: Add ACPI support for xHCI ports

The ACPI companion of the adapter has to be set for xHCI controller
code to read and attach the ports described in the ACPI table.
Use ACPI_COMPANION_SET macro to set this.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>