dmaengine: qcom_hidma: pause the channel on shutdown

We need to ensure that all DMAs and interrupts are cleared during
shutdown operation in order for kexec to start the next kernel clearly.

Otherwise, HW could be performing a DMA into random addresses in the
middle of second kernel start.

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>