If the DMA engine doesn't support residue processing then the RX DMA
handling won't work terribly well if polling is enabled.  So, disable
RX DMA if residue handling isn't available.
Signed-off-by: NAndrew Jackson <Andrew.Jackson@arm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>