regulator: core: Release coupled_rdevs on regulator_init_coupling() error

This patch fixes memory leak which should happen if regulator's coupling
fails to initialize.

Fixes: d8ca7d18 ("regulator: core: Introduce API for regulators coupling customization")
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Link: https://lore.kernel.org/r/20191025002240.25288-1-digetx@gmail.com


Signed-off-by: Mark Brown <broonie@kernel.org>