regulator: Update LDO2 for WM8958

LDO2 has a slightly different range of supported voltages on WM8958
so update the selector<->voltage mappings to match.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>