dmaengine: move link order

Move the dmaengine subsystem up early in the drivers Makefile so
DMA is made available early to all drivers, just like e.g.
regulators. Now even regulators can use DMA on the same initlevel.
As a result we can bump the ste_dma40 and coh901318 dmaengine
drivers down one initlevel to subsys_init().

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>