Revert "regulator: core: Fix nested locking of supplies"

This reverts commit b1999fa6 which was
commit 70a7fb80 upstream.

It causes run-time breakage in the 4.4-stable tree and more patches are
needed to be applied first before this one in order to resolve the
issue.
Reported-by: Guenter Roeck <linux@roeck-us.net>
Cc: Mark Brown <broonie@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Thierry Reding <treding@nvidia.com>
Cc: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/regulator/core.c

@@ -132,14 +132,6 @@ static bool have_full_constraints(void)
 	return has_full_constraints || of_have_populated_dt();
 }
 
-static inline struct regulator_dev *rdev_get_supply(struct regulator_dev *rdev)
-{
-	if (rdev && rdev->supply)
-		return rdev->supply->rdev;
-
-	return NULL;
-}
-
 /**
  * regulator_lock_supply - lock a regulator and its supplies
  * @rdev:         regulator source
@@ -148,7 +140,7 @@ static void regulator_lock_supply(struct regulator_dev *rdev)
 {
 	int i;
 
-	for (i = 0; rdev->supply; rdev = rdev_get_supply(rdev), i++)
+	for (i = 0; rdev->supply; rdev = rdev->supply->rdev, i++)
 		mutex_lock_nested(&rdev->mutex, i);
 }