Save the current RX and TX DMA devices to avoid having to duplicate the
logic to pick them, since we'll need access to them in some more
functions to fix a bug in the cache handling.
Signed-off-by: NVincent Whitchurch <vincent.whitchurch@axis.com>
Link: https://lore.kernel.org/r/20220927112117.77599-2-vincent.whitchurch@axis.comSigned-off-by: NMark Brown <broonie@kernel.org>