dmaengine: shdmac: use SET_RUNTIME_PM_OPS()

Use SET_RUNTIME_PM_OPS() to initialize the runtime PM method pointers in the
'struct dev_pm_ops';  since that macro doesn't  do anything  if CONFIG_PM is
not defined, we have  to move #ifdef up to also cover the runtime PM methods
in order to avoid compilation warnings.

Based on orignal patch by Mikhail Ulyanov <mikhail.ulyanov@cogentembedded.com>.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>