regulator: core: Fix memory leak in regulator_resolve_supply()

The regulator_resolve_supply() function calls set_supply() which in turn
calls create_regulator() to allocate a supply regulator.

If an error occurs after set_supply() succeeded, the allocated regulator
has to be freed before propagating the error code.

Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Mark Brown <broonie@kernel.org>