mmc: tmio: fix a recently introduced bug in DMA code

A recent commit "mmc: tmio: Share register access functions" has swapped
arguments of a macro and broken DMA with TMIO MMC. This patch fixes the
arguments back.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Chris Ball <cjb@laptop.org>