dmaengine: mpc512x: Implement additional chunk sizes for DMA transfers

This patch extends the capabilities of the driver to handle DMA
transfers to and from devices of 1, 2, 4, 16 (for MPC512x), and 32 byte
widths.

Signed-off-by: Mario Six <mario.six@gdsys.cc>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>