regulator: s5m8767: Convert to use regulator_[enable|disable|is_enabled]_regmap

Since commit ca5d1b35
"regulator: helpers: Modify helpers enabling multi-bit control",
we can set enable_val setting for device that use multiple bits for control.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Tested-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Reviewed-by Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Mark Brown <broonie@linaro.org>