dmaengine: initialise DMA engine before MMC

To use DMA engine based DMA with MMC in a non-modular build, the DMA
engine has to initialise before MMC.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>