The (undocumented) possible values for the buck operating modes on the
MT6358 are the same as those on the MT6397, both for the device tree
bindings and the actual hardware register values.
Reuse the macros for the MT6397 PMIC in the MT6358 regulator driver by
including the mt6397-regulator.h binding header and replacing the
existing macros. This aligns it with other PMIC.
Signed-off-by: Chen-Yu Tsai <wenst@xxxxxxxxxxxx>