MLK-18248: dma: fsl-edma-v3: avoid touch unused edma channel

Avoid touch unused edma channel register in susped/resume, otherwise,
kernel crash if XRDC enabled in scfw.

Signed-off-by: Robin Gong <yibin.gong@nxp.com>
Acked-by: Fugang Duan <fugang.duan@nxp.com>
Signed-off-by: Vipul Kumar <vipul_kumar@mentor.com>
Signed-off-by: Srikanth Krishnakar <Srikanth_Krishnakar@mentor.com>