spi: spi-s3c64xx: Do not ignore timeout errors in polling I/O mode

Currently timeout errors in polling I/O mode transfer are silently ignored.
Fix it by returning an error when we time out waiting on the RX FIFO level
to reach the transfer length.
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Reviewed-by: Andi Shyti <andi@etezian.org>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-s3c64xx.c

@@ -503,6 +503,8 @@ static int wait_for_pio(struct s3c64xx_spi_driver_data *sdd,
 		status = readl(regs + S3C64XX_SPI_STATUS);
 	} while (RX_FIFO_LVL(status, sdd) < xfer->len && --val);
 
+	if (!val)
+		return -EIO;
 
 	/* If it was only Tx */
 	if (!xfer->rx_buf) {