of: dma: Split of_configure_dma() into mask and ops configuration

of: dma: Split of_configure_dma() into mask and ops configuration

The of_configure_dma() function configures both the DMA masks and ops.
Moving DMA ops configuration to probe time would thus also delay
configuration of the DMA masks, which might not be safe. To avoid issues
split the configuration in two to allow keeping masks configuration at
device add time and move ops configuration to device probe time.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>