The voltage_mask is 0xc0, thus we need to set voltage_shift = 6 to get correct
selector in get_voltage_sel and set_voltage_sel.
Signed-off-by: Axel Lin <axel.lin@ingics.com> Acked-by: Bengt Jonsson <bengt.g.jonsson@stericsson.com> Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>