mmc: sdhi/tmio: make DMA filter implementation specific

So far only the SDHI implementation uses TMIO MMC with DMA. That way a DMA
channel filter function, defined in the TMIO driver wasn't a problem.
However, such a filter function is DMA controller specific. Since the SDHI
glue is only running on systems with the SHDMA DMA controller, the filter
function can safely be provided by it. Move it into SDHI.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski+renesas@gmail.com>
Acked-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Chris Ball <cjb@laptop.org>