mtd: spi-nor: cadence-quadspi: Don't initialize rx_dma_complete on failure

If driver fails to acquire DMA channel then don't initialize
rx_dma_complete struct as it won't be used.
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Acked-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Link: https://lore.kernel.org/r/20200601070444.16923-4-vigneshr@ti.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/mtd/spi-nor/controllers/cadence-quadspi.c

@@ -1180,6 +1180,7 @@ static void cqspi_request_mmap_dma(struct cqspi_st *cqspi)
 	if (IS_ERR(cqspi->rx_chan)) {
 		dev_err(&cqspi->pdev->dev, "No Rx DMA available\n");
 		cqspi->rx_chan = NULL;
+		return;
 	}
 	init_completion(&cqspi->rx_dma_complete);
 }