regulator: pv88060: Fix .ops for PV88060_SW

There is no vsel_reg/vsel_mask settings for PV88060_ID_SWx, so don't use
pv88060_ldo_ops for PV88060_SW. The PV88060_ID_SWx is fixed voltage,
set .fixed_uV instead of .min_uV then regulator core will automatically
support get_voltage and list_voltage.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@kernel.org>