drivers: video: common: API misuse in video_closest_frmival()

[josuah]

Describe the bug

video_closest_frmival() is expecting the driver to increment fie.index. This is not the correct API and having this in video_common.c and video_emul_imager.c is misleading. The tests is also wrong.

To Reproduce

The CI passes while it should fail as the test is testing the wrong thing:

zephyr/tests/drivers/video/api/src/video_emul.c

Lines 84 to 86 in 493be79

	/* Do a first enumeration of frame intervals, expected to work */
	zexpect_ok(video_enum_frmival(imager_dev, VIDEO_EP_OUT, &fie));
	zexpect_equal(fie.index, 1, "fie's index should increment by one at every iteration");

Expected behavior

The driver does not increment fie.index, the caller does.

Impact

No public code currently uses it, but developers building new code will be confused.

Logs and console output

Environment (please complete the following information):

CI

Additional context

A PR to fix it is already proposed here:

• drivers: video: imager: move the boilerplate in a library #88003

But only one commit out of it is for the actual fix and can be split:

• fd3677d