serial: 8250_dw: support ACPI platforms with integrated DMA engine

On many new Intel SoCs the UART has an integrated DMA engine
(iDMA). In order to use it a special filter function is needed.

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