serial: 8250_dw: Enable DMA support with ACPI

With ACPI 5.0 we can use the FixedDMA Resource Descriptor to
extract the needed information for DMA support.

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>