gpio: stm32_gpio: Rework GPIO hole management

On some STM32 SoC's package, GPIO bank may have hole in their GPIO bank Example: If GPIO bank have 16 GPIO pins [0-15]. In particular SoC's package case, some GPIO bank can have less GPIO pins: - [0-10] => 11 pins; - [2-7] => 6 pins.

Commit dbf928dd ("gpio: stm32f7: Add gpio bank holes management") proposed a first implementation by not counting GPIO "inside" hole. GPIO are not displaying correctly using gpio or pinmux command when GPIO holes are located at the beginning of GPIO bank.

To simplify, consider that all GPIO have 16 GPIO and use the gpio_ranges struct to indicate if a GPIO is mapped or not. GPIO uclass offers several GPIO functions ("input", "output", "unused", "unknown" and "func"), use "unknown" GPIO function to indicate that a GPIO is not mapped.

stm32_offset_to_index() is no more needed and removed.

This must be reflected using the "gpio" command to indicate to user that a particular GPIO is not mapped (marked as "unknown") as shown below:

Example for a 16 pins GPIO bank with the [2-7] mapping (only 6 pins mapped): GPIOI0 : unknown GPIOI1 : unknown GPIOI2 : analog GPIOI3 : analog GPIOI4 : alt function 0 push-pull pull-down GPIOI5 : alt function 0 push-pull pull-down GPIOI6 : alt function 0 push-pull pull-down GPIOI7 : analog GPIOI8 : unknown GPIOI9 : unknown GPIOI10 : unknown GPIOI11 : unknown GPIOI12 : unknown GPIOI13 : unknown GPIOI14 : unknown GPIOI15 : unknown

Signed-off-by: Patrice Chotard patrice.chotard@foss.st.com Change-Id: I55c39a2707fa8dae108d90c4a72590f1a4520ca9