dt-bindings: pinctrl: stm32: support for stm32mp257 and additional packages

Add support for st,stm32mp257-pinctrl and st,stm32mp257-z-pinctrl.
Add packages AI, AK and AL (values : 0x100, 0x400 and 0x800)

Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>