spi: spi-cadence-quadspi: Return EPROBE_DEFER on dma failure

Depending on the probing order of dma vs ospi, dma failure is seen when
ospi controller probes first and checks for available dma channel and
fails. This patch fixes it by sending EPROBE_DEFER, which helps acquire
dma channel after the dma controller probes.

Signed-off-by: Prasanth Babu Mantena <p-mantena@ti.com>
Signed-off-by: Santhosh Kumar K <s-k6@ti.com>

drivers/spi/spi-cadence-quadspi.c

@@ -2455,7 +2455,7 @@ static int cqspi_request_mmap_dma(struct cqspi_st *cqspi)
 
 	cqspi->rx_chan = dma_request_chan_by_mask(&mask);
 	if (IS_ERR(cqspi->rx_chan)) {
-		int ret = PTR_ERR(cqspi->rx_chan);
+		int ret = (-EPROBE_DEFER);
 
 		cqspi->rx_chan = NULL;
 		return dev_err_probe(&cqspi->pdev->dev, ret, "No Rx DMA available\n");