dm: power: Use debug() for errors in regulator uclass

To reduce unnecessary code size in an uncommon code path, use debug()
where possible(). The driver returns an error which indicates failure.

Signed-off-by: Simon Glass <sjg@chromium.org>
Tested-by: Przemyslaw Marczak <p.marczak@samsung.com>
Acked-by: Przemyslaw Marczak <p.marczak@samsung.com>
diff --git a/drivers/power/regulator/regulator-uclass.c b/drivers/power/regulator/regulator-uclass.c
index a2d0b9f..12e141b 100644
--- a/drivers/power/regulator/regulator-uclass.c
+++ b/drivers/power/regulator/regulator-uclass.c
@@ -262,7 +262,7 @@
 	if (regulator_name_is_unique(dev, uc_pdata->name))
 		return 0;
 
-	error("\"%s\" of dev: \"%s\", has nonunique value: \"%s\"",
+	debug("\"%s\" of dev: \"%s\", has nonunique value: \"%s\"",
 	      property, dev->name, uc_pdata->name);
 
 	return -EINVAL;