exynos: spi: Convert the timeout to debug()

Since the timeout is reported through normal channels, and is sometimes
expected (e.g. if the bus is being probed for a non-existent device),
don't display the message in the driver.

In general, drivers should not write to the console as this limits their
usefulness in error conditions.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/spi/exynos_spi.c b/drivers/spi/exynos_spi.c
index 67f6b2d..6d77c31 100644
--- a/drivers/spi/exynos_spi.c
+++ b/drivers/spi/exynos_spi.c
@@ -190,9 +190,9 @@
 			spi_request_bytes(regs, toread, step);
 		}
 		if (priv->skip_preamble && get_timer(start) > 100) {
-			printf("SPI timeout: in_bytes=%d, out_bytes=%d, ",
-			       in_bytes, out_bytes);
-			return -1;
+			debug("SPI timeout: in_bytes=%d, out_bytes=%d, ",
+			      in_bytes, out_bytes);
+			return -ETIMEDOUT;
 		}
 	}