regulator: core: Log forbidden DRMS operation

When REGULATOR_CHANGE_DRMS is not set, drms_uA_update is a no-op.
It used to print a debug message, which was dropped in commit
8a34e979 ("regulator: refactor valid_ops_mask checking code")

Let's bring the debug message back, because it helps find missing
regulator-allow-set-load properties.
Signed-off-by: NMarc Gonzalez <marc.w.gonzalez@free.fr>
Signed-off-by: NMark Brown <broonie@kernel.org>

drivers/regulator/core.c

@@ -918,8 +918,10 @@ static int drms_uA_update(struct regulator_dev *rdev)
 	 * first check to see if we can set modes at all, otherwise just
 	 * tell the consumer everything is OK.
 	 */
-	if (!regulator_ops_is_valid(rdev, REGULATOR_CHANGE_DRMS))
+	if (!regulator_ops_is_valid(rdev, REGULATOR_CHANGE_DRMS)) {
+		rdev_dbg(rdev, "DRMS operation not allowed\n");
 		return 0;
+	}
 
 	if (!rdev->desc->ops->get_optimum_mode &&
 	    !rdev->desc->ops->set_load)