dmaengine: fsl-edma-common: move dmamux register to another single function

Prepare for edmav2 on i.mx7ulp whose dmamux register is 32bit. No function
impacted.

Signed-off-by: Robin Gong <yibin.gong@nxp.com>
Tested-by: Angelo Dureghello <angelo@sysam.it>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
1 file changed