spi: spi-ti-qspi: Fix return value handling of wait_for_completion_timeout

wait_for_completion_timeout() returns unsigned long not int.
It returns 0 if timed out, and positive if completed.
The check for <= 0 is ambiguous and should be == 0 here
indicating timeout which is the only error case.

Fixes: 5720ec0a ("spi: spi-ti-qspi: Add DMA support for QSPI mmap read")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Link: https://lore.kernel.org/r/20220411111034.24447-1-linmq006@gmail.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-ti-qspi.c

@@ -448,6 +448,7 @@ static int ti_qspi_dma_xfer(struct ti_qspi *qspi, dma_addr_t dma_dst,
 	enum dma_ctrl_flags flags = DMA_CTRL_ACK | DMA_PREP_INTERRUPT;
 	struct dma_async_tx_descriptor *tx;
 	int ret;
+	unsigned long time_left;
 
 	tx = dmaengine_prep_dma_memcpy(chan, dma_dst, dma_src, len, flags);
 	if (!tx) {
@@ -467,9 +468,9 @@ static int ti_qspi_dma_xfer(struct ti_qspi *qspi, dma_addr_t dma_dst,
 	}
 
 	dma_async_issue_pending(chan);
-	ret = wait_for_completion_timeout(&qspi->transfer_complete,
+	time_left = wait_for_completion_timeout(&qspi->transfer_complete,
 					  msecs_to_jiffies(len));
-	if (ret <= 0) {
+	if (time_left == 0) {
 		dmaengine_terminate_sync(chan);
 		dev_err(qspi->dev, "DMA wait_for_completion_timeout\n");
 		return -ETIMEDOUT;