clk: tegra: Don't warn three times about failure to unregister

tegra124_dfll_fcpu_remove() calls tegra_dfll_unregister() and the former
emits an error message if the latter fails. In that case
tegra_dfll_unregister() already printed an error message. Additionally
tegra124_dfll_fcpu_remove() returns an error code which results in yet
another warning emitted by platform_remove().

So drop the error message from tegra124_dfll_fcpu_remove() and let it
return 0. (Retuning 0 has no side effect but suppressing the error
message in platform_remove().)

Also add two comments about exiting early being wrong. This is something
that needs fixing separately.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20230312161512.2715500-3-u.kleine-koenig@pengutronix.de
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

Author: Uwe Kleine-König

drivers/clk/tegra/clk-dfll.c

@@ -2081,7 +2081,10 @@ struct tegra_dfll_soc_data *tegra_dfll_unregister(struct platform_device *pdev)
 {
 	struct tegra_dfll *td = platform_get_drvdata(pdev);
 
-	/* Try to prevent removal while the DFLL is active */
+	/*
+	 * Note that exiting early here doesn't prevent unbinding the driver.
+	 * Exiting early here only leaks some resources.
+	 */
 	if (td->mode != DFLL_DISABLED) {
 		dev_err(&pdev->dev,
 			"must disable DFLL before removing driver\n");

drivers/clk/tegra/clk-tegra124-dfll-fcpu.c

@@ -616,12 +616,13 @@ static int tegra124_dfll_fcpu_remove(struct platform_device *pdev)
 {
 	struct tegra_dfll_soc_data *soc;
 
+	/*
+	 * Note that exiting early here is dangerous as after this function
+	 * returns *soc is freed.
+	 */
 	soc = tegra_dfll_unregister(pdev);
-	if (IS_ERR(soc)) {
-		dev_err(&pdev->dev, "failed to unregister DFLL: %ld\n",
-			PTR_ERR(soc));
-		return PTR_ERR(soc);
-	}
+	if (IS_ERR(soc))
+		return 0;
 
 	tegra_cvb_remove_opp_table(soc->dev, soc->cvb, soc->max_freq);