regulator: s5m8767: Convert to GPIO descriptors

Merge series from From git@z Thu Jan  1 00:00:00 1970
Peng Fan <peng.fan@nxp.com>:

Update the driver to fetch buck_gpio and buck_ds as GPIO descriptors.
Then drop the usage of 'of_gpio.h' which should be deprecated.
Based on commit 84618d5e ("regulator: max8997:
Convert to GPIO descriptors") as a reference to make the changes.

With the quirk fix for s5m8767 in of_gpio_try_fixup_polarity,
the polarity will be active-high, even if exynos5250 spring DTS
wrongly use active-low polarity. So using GPIO descriptors,
it should work as before.