regulator: remove superfluous lock in regulator_resolve_coupling()

The code modifies rdev, but locks c_rdev instead. Remove the lock
as this is held together by regulator_list_mutex taken in the caller.

Fixes: f950338 ("regulator: core: Mutually resolve regulators coupling")
Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Link: https://lore.kernel.org/r/25eb81cefb37a646f3e44eaaf1d8ae8881cfde52.1597195321.git.mirq-linux@rere.qmqm.pl
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: osctobe

drivers/regulator/core.c

@@ -4972,13 +4972,9 @@ static void regulator_resolve_coupling(struct regulator_dev *rdev)
 			return;
 		}
 
-		regulator_lock(c_rdev);
-
 		c_desc->coupled_rdevs[i] = c_rdev;
 		c_desc->n_resolved++;
 
-		regulator_unlock(c_rdev);
-
 		regulator_resolve_coupling(c_rdev);
 	}
 }