regulator: max1586: Don't allocate memory for regulator_dev pointers

Do not allocate memory for 'struct regulator_dev *' since it was removed
from state container (values returned by devm_regulator_register() are
not used outside of probe).

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