tty: serial: 8250-of: Do not warn on deferred probe

Deferred probe is an expected return value for clk_get() on many
platforms. The driver deals with it properly, so there's no need
to output a warning that may potentially confuse users.
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/8250_of.c

@@ -70,9 +70,10 @@ static int of_platform_serial_setup(struct platform_device *ofdev,
 		/* Get clk rate through clk driver if present */
 		info->clk = devm_clk_get(&ofdev->dev, NULL);
 		if (IS_ERR(info->clk)) {
-			dev_warn(&ofdev->dev,
-				"clk or clock-frequency not defined\n");
 			ret = PTR_ERR(info->clk);
+			if (ret != -EPROBE_DEFER)
+				dev_warn(&ofdev->dev,
+					 "failed to get clock: %d\n", ret);
 			goto err_pmruntime;
 		}