regulator: max77686: Initialize opmode explicitly to normal mode

Minor nit: Initialize the opmode for each regulator to normal mode in a
readable explicit way.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Suggested-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Reviewed-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Signed-off-by: Mark Brown <broonie@kernel.org>