intel_mid_dma: fix runtime pm issues

Use the correct api in probe to enable runtime pm for this driver.
Additionally, do not just call legacy suspend for runtime_suspend,
as this duplicates some work the pci core does for you.

Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>