dmaengine: remove BUG_ON while registering devices

DMAengine core has BUG_ON to check for mandatory operations and ones based
on capabilities, but they use BUG_ON, so remove and move to error returns
and logging the errors gracefully

Acked-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>