pinctrl: qcom: spmi-gpio: Add support for GPIO LV/MV subtype

GPIO LV (low voltage)/MV (medium voltage) subtypes have different
features and register mappings than 4CH/8CH subtypes. Add support
for LV and MV subtypes.

Change-Id: I7bcf4347adce6ba9892d2e57a413d407d35fbc26
Signed-off-by: Fenglin Wu <fenglinw@codeaurora.org>