MLK-19418-3: dmaengine: imx-sdma: remove context load in sdma_channel_resume

Since sdma_resume will restore all context in case sdma power off after
suspend, sdma_channel_resume does not need to restore again. Besides,
'suspend_off' can be removed too.

Signed-off-by: Robin Gong <yibin.gong@nxp.com>
Reviewed-by: Shengjiu Wang <shengjiu.wang@nxp.com>
Signed-off-by: Vipul Kumar <vipul_kumar@mentor.com>
Signed-off-by: Srikanth Krishnakar <Srikanth_Krishnakar@mentor.com>