regulator: max77693: Fix use of uninitialized regulator config

Driver allocated on stack struct regulator_config but didn't initialize
it fully. Few fields (driver_data, ena_gpio) were left untouched. This
lead to using random ena_gpio values as GPIOs for max77693 regulators.

On occasion these values could match real GPIO numbers leading to
interfering with other drivers and to unsuccessful enable/disable of
regulator.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Fixes: 80b022e29bfd ("regulator: max77693: Add max77693 regualtor driver.")
Cc: <stable@vger.kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>