dmaengine: xilinx: dpdma: Fix spacing around addr[i-1]

Use proper spacing for array calculation. Issue is reported by
checkpatch.pl --strict.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://lore.kernel.org/r/ef7cde6f793bfa6f3dd0a8898bad13b6407479b0.1624446456.git.michal.simek@xilinx.com


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