drivers: gpio: Place API into iterable section

[pdgendt]

Add wrapper DEVICE_API macro to all gpio_driver_api instances.

[yishai1999]

Maybe adapt gpio_shell.c to use the API check instead of what it does now which is check that the gpio-controller property exists.

[henrikbrixandersen]

Maybe adapt gpio_shell.c to use the API check instead of what it does now which is check that the gpio-controller property exists.

I'm a big fan of smaller, self-contained PRs. I'd suggest to leave all shell changes out of the PRs moving the API structs, and do small, incremental follow-up PRs instead.

[pdgendt]

Yes, I planned to do some follow-up PRs for that, this should be as simple as possible to review as many reviewers are pulled in.

[dleach02]

Somehow I get to be the assignee for all these "iterable section" PRs. Do we have a place in our documentation that should be updated with this guidance?

[pdgendt]

Somehow I get to be the assignee for all these "iterable section" PRs. Do we have a place in our documentation that should be updated with this guidance?

The device driver model page has been updated. I don't really know why you got assigned in all of these, but NXP drivers are changed too.