mmc_spi: add a status check for spi_sync_locked

In case spi_sync_locked fails, the fix reports the error and
returns the error code upstream.
Signed-off-by: Kangjie Lu <kjlu@umn.edu>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/mmc_spi.c

@@ -819,6 +819,10 @@ mmc_spi_readblock(struct mmc_spi_host *host, struct spi_transfer *t,
 	}
 
 	status = spi_sync_locked(spi, &host->m);
+	if (status < 0) {
+		dev_dbg(&spi->dev, "read error %d\n", status);
+		return status;
+	}
 
 	if (host->dma_dev) {
 		dma_sync_single_for_cpu(host->dma_dev,