MLK-20598 dmaengine: imx-sdma: fix potential system hang

MLK-20598 dmaengine: imx-sdma: fix potential system hang

In multi audio play/stop case,sdma_alloc_chan_resources/
sdma_free_chan_resources will be called quickly, especially,dma done
interrupt comes after sdma_free_chan_resources, thus, system will be
hang in interrupt since it'll check sdma register but clocks have
already been disabled in sdma_free_chan_resources. To avoid it, enable
clock in isr.

Signed-off-by: Robin Gong <yibin.gong@nxp.com>
Signed-off-by: Arulpandiyan Vadivel <arulpandiyan_vadivel@mentor.com>
Signed-off-by: Shrikant Bobade <Shrikant_Bobade@mentor.com>
(cherry picked from commit 09b55a84522fbf404d6cd82b4640a93672c2aa27)