serial: 8250dw: Add device HID for future AMD UART controller

Add device HID AMDI0020 to match the AMD ACPI Vendor ID (AMDI) as
registered in http://www.uefi.org/acpi_id_list

, and the UART
controller on future AMD paltform will use the HID instead of AMD0020.

Signed-off-by: Wang Hongcheng <annie.wang@amd.com>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>