dmaengine: Add Freescale i.MX1/21/27 DMA driver

This driver is currently implemented as a user to the old i.MX
DMA API. This allows us to convert each user of the old API to
the dmaengine API one by one. Once this is done the old DMA
driver can be merged into the i.MX dmaengine driver.

V2: remove some debug leftovers and unused variables

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>