dmaengine: imx-sdma: Add support for version 3 firmware

Currently when version 3.1 of the mx6q SDMA firmware is used we get:

[    0.392169] imx-sdma 20ec000.sdma: unknown firmware version
[    0.399281] imx-sdma 20ec000.sdma: initialized

Add support for it.

Based on a patch from Shengjiu Wang from the internal FSL kernel.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>