[media] v4l: omap3isp: Use dma_request_chan_by_mask() to request the DMA channel
When requesting the DMA channel it was mandatory that we do not have DMA
resource nor valid DMA channel via DT. In this case the
dma_request_slave_channel_compat() would fall back and request any channel
with SW trigger.
The same can be achieved with the dma_request_chan_by_mask() without the
misleading use of the DMAengine API - implying that the omap3isp does
need to have DMA resource or valid dma binding in DT.