DMA: Convert from class_device to device for DMA engine

Signed-off-by: Tony Jones <tonyj@suse.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: Shannon Nelson <shannon.nelson@intel.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>