dmaengine: Driver support for FSL RaidEngine device.

The RaidEngine is a new FSL hardware used for Raid5/6 acceration.
This patch enables the RaidEngine functionality and provides
hardware offloading capability for memcpy, xor and pq computation.
It works with async_tx.

Signed-off-by: Harninder Rai <harninder.rai@freescale.com>
Signed-off-by: Xuelin Shi <xuelin.shi@freescale.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>