regulator: pf8x00: use linear range for buck 1-6

Use a linear range to describe the voltages of the
bucks 1-6 instead of listing it one by one (via a macro)

Signed-off-by: Adrien Grassein <adrien.grassein@gmail.com>
Link: https://lore.kernel.org/r/20210114174714.122561-6-adrien.grassein@gmail.com


Signed-off-by: Mark Brown <broonie@kernel.org>