Add stm32_pctrl_get_desc_pin_from_gpio function to find a stm32 pin
descriptor which is matching with a gpio.
Most of the time pin number is equal to pin index in array. So the first
part of the function is useful to speed up.

And during gpio bank register, we set default gpio names with pin names.
Signed-off-by: Valentin Caron <valentin.caron@foss.st.com>
Acked-by: Alexandre TORGUE <alexandre.torgue@foss.st.com>
Link: https://lore.kernel.org/r/20230620104349.834687-1-valentin.caron@foss.st.comSigned-off-by: Linus Walleij <linus.walleij@linaro.org>