This control signal can be overwritten by the up_axis_xlast/up_axis_xlast_en bits, in order to create a single stream, which is contains multiple streams.
This can be use to fill up the DACFIFO module.
There were a few place in the core where it assumed a 64-bit wide bus. Make this
configurable using parameters. The patch also adds support for having different
DMA bus widths on the source and destination side.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>