gpio: msm: fix get_function return for special pins

gpio: msm: fix get_function return for special pins

The get_function callback wrongly returns 0 for special pins,
return the appropriate pin function by probing into the special
pins data fields to find if the pin is gpio capable.

Fixes: f9bb539460d ("gpio: msm: add support for special pins")
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20250401-topic-sm8x50-msm-gpio-special-fixes-v1-1-a1148a02bb16@linaro.org
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>