dmaengine: xilinx: dpdma: remove comparison of unsigned expression

dmaengine: xilinx: dpdma: remove comparison of unsigned expression

xilinx_dpdma_config() channel id is unsigned int and compares with
ZYNQMP_DPDMA_VIDEO0 which is zero, so remove this comparison

drivers/dma/xilinx/xilinx_dpdma.c:1073:15: warning: comparison of
unsigned expression in ‘>= 0’ is always true [-Wtype-limits] if
	(chan->id >= ZYNQMP_DPDMA_VIDEO0 && chan->id <= ZYNQMP_DPDMA_VIDEO2)

Link: https://lore.kernel.org/r/20200718135201.191881-1-vkoul@kernel.org
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>