dmaengine: omap-dma: Implement protection for invalid max_burst

the device's max_burst to 16777215 (EN is 24bit unsigned 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>
Cc: Russell King <linux@armlinux.org.uk>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>