regulator: max77686: Remove regulator_dev array from state container

Don't store array of regulator_dev returned by devm_regulator_register()
in state container. It isn't used anywhere outside of
max77686_pmic_probe() function.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Mark Brown <broonie@linaro.org>