dmaengine: dw-edma: Remove unused irq field in struct dw_edma_chip

dmaengine: dw-edma: Remove unused irq field in struct dw_edma_chip

The "irq" field of struct dw_edma_chip was never used. Remove it.

Link: https://lore.kernel.org/r/20220524152159.2370739-2-Frank.Li@nxp.com
Tested-by: Serge Semin <fancer.lancer@gmail.com>
Tested-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Serge Semin <fancer.lancer@gmail.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Acked-By: Vinod Koul <vkoul@kernel.org>