as esp-idf has introduced a new public one: esp_ldo_regulator.h
Note, this is not a breaking change as the legacy driver doesn't exist
on any release branch.
Prior to this commit, we expect passing ldo_unit_t to esp_ldo driver
`ldo_unit` field. And ldo_unit_t will alias the LDO unit to values
starting from 0, e.g. LDO_UNIT_1 is actually value 0.
With this commit, esp_ldo driver `ldo_unit` field will start with 1,
which is aligned with the datasheet. So LDO_UNIT_1 is in value 1,
meanwhile setting 1 to `ldo_unit` will work as well.
