spi/s3c64xx: Complain if we fail to set a transfer speed

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
index ad93231..6495352 100644
--- a/drivers/spi/spi-s3c64xx.c
+++ b/drivers/spi/spi-s3c64xx.c
@@ -957,6 +957,8 @@
 		if (spi->max_speed_hz >= speed) {
 			spi->max_speed_hz = speed;
 		} else {
+			dev_err(&spi->dev, "Can't set %dHz transfer speed\n",
+				spi->max_speed_hz);
 			err = -EINVAL;
 			goto setup_exit;
 		}