dmaengine: xilinx: xdma: Get rid of unused code

Get rid of duplicated macro definitions, as these macros are defined
earlier in the file. Also, get rid of unused member
of 'struct xdma_desc'.

Signed-off-by: Jan Kuliga <jankul@alatek.krakow.pl>
Link: https://lore.kernel.org/r/20231218113943.9099-2-jankul@alatek.krakow.pl


Signed-off-by: Vinod Koul <vkoul@kernel.org>