Move away from statically allocated GPIO IDs. Switch to dynamic ID
allocation. Static IDs are deprecated because they cause issues when
multiple GPIO controllers are to be found on the same platform.

Add a bit of complexity to do pin number -> GPIO chip + offset.
Previously, bank number and offsets were retrieved using division and
remainder (bank size being constant 32). Now, to get the pin number
matching a bank base, we must know the sum of ngpios of previous banks.
This is done in find_nmk_gpio_from_pin() which also exposes the offset
inside the bank.

Also remove the assumption that bank sizes are constant. Instead of
using NMK_GPIO_PER_CHIP as bank size, use nmk_gpio_chips[i]->ngpio.
Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
Link: https://lore.kernel.org/r/20240228-mbly-gpio-v2-19-3ba757474006@bootlin.comSigned-off-by: Linus Walleij <linus.walleij@linaro.org>