DMA engine driver might not always provide all the features needed by
serial driver to properly operate in DMA mode, so check that before
selecting DMA mode.
Signed-off-by: NMarek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: NKrzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>