Pickable ranges mapping function never used range min selector. Thus
existing drivers broke when proper linear_ranges functionality was taken
in use. Fix this for now just by ignoring the minimum selector.

Fixes: 60ab7f41 ("regulator: use linear_ranges helper")
Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Link: https://lore.kernel.org/r/20200612090225.GA3243@localhost.localdomainSigned-off-by: Mark Brown <broonie@kernel.org>