dmaengine: edma: Implement protection for invalid max_burst

the device's max_burst to 32767 (CIDX is 16bit signed value) so clients
can take this into consideration when setting up the transfer.

During slave transfer preparation check if the requested maxburst is valid.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>