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.

Signed-off-by: Fenglin Wu <fenglinw@codeaurora.org>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>