Add pmic-gpio compatible string for pm6350 pmic.
Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
Link: https://lore.kernel.org/r/20211007212444.328034-5-luca@z3ntu.xyzSigned-off-by: Linus Walleij <linus.walleij@linaro.org>