pinctrl: qcom: use generic pin function helpers

pinctrl: qcom: use generic pin function helpers

With the pinmux core no longer duplicating memory used to store the
struct pinfunction objects in .rodata, we can now use the existing
infrastructure for storing and looking up pin functions in qualcomm
drivers. Remove hand-crafted callbacks.

Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Tested-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>