The driver was registering buck regulators with unsupported range of
voltages for S2MPS11 devices.  Basically it assumed that all 256 values
are possible for a single 8-bit I2C register controlling buck's voltage.
This is not true, as datasheet describes subset of these which can be
used.

For example for buck[12346] the minimum voltage is 650 mV which
corresponds to register value of 0x8.  The driver was however
registering regulator starting at 600 mV, so for a step of 6.25 mV this
gave the same result.  However this allowed to try to configure
regulators to unsupported values.

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