regulator: core: Fix more error checking for debugfs_create_dir()

In case of failure, debugfs_create_dir() does not return NULL, but an
error pointer.  Most incorrect error checks were fixed, but the one in
create_regulator() was forgotten.

Fix the remaining error check.

Fixes: 2bf1c45be3 ("regulator: Fix error checking for debugfs_create_dir")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/ee980a108b5854dd8ce3630f8f673e784e057d17.1685013051.git.geert+renesas@glider.be
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/core.c

@@ -1911,7 +1911,7 @@ static struct regulator *create_regulator(struct regulator_dev *rdev,
 
 	if (err != -EEXIST)
 		regulator->debugfs = debugfs_create_dir(supply_name, rdev->debugfs);
-	if (!regulator->debugfs) {
+	if (IS_ERR(regulator->debugfs)) {
 		rdev_dbg(rdev, "Failed to create debugfs directory\n");
 	} else {
 		debugfs_create_u32("uA_load", 0444, regulator->debugfs,