regulator: Fix memory leak in set_machine_constraints() error paths

Properly kfree rdev->constraints in all set_machine_constraints() error paths.
Also properly kfree rdev->constraints in regulator_register() error paths.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>