dmaengine: mmp_pdma: fix warning about slave caps

Fix the dmaengine complaint about missing slave caps :
 - declare the available bus widths
 - declare the available transfer types
 - declare the residue calculation type

Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>