Simplify the driver by removing board file support and letting
regulator core to parse DT.

The max77693 regulator driver is used only on Exynos based boards which
are DT-only. Board files for Exynos are not supported.
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Mark Brown <broonie@kernel.org>