sdm670_reserved_gpios is only used in pinctrl-sdm670.c now, change it
to static.

Fixes: 61164d22 ("pinctrl: qcom: add sdm670 pinctrl")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Link: https://lore.kernel.org/r/20221020075650.1031228-1-yangyingliang@huawei.comAcked-by: Richard Acayan <mailingradian@gmail.com>
[Fix up subject]
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>