The stm32 gpio driver private data are not needed in arch include files,
they are not used by code except for stm32 gpio and pincontrol drivers,
using the same IP; the defines for this IP is moved in a new file
"stm32_gpio_priv.h" in driver/gpio.

This patch avoids to have duplicated file gpio.h for each SOC
in MPU directory mach-stm32mp and in each MCU directory arch-stm32*
and allows to remove CONFIG_GPIO_EXTRA_HEADER for all STM32.

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>