video_flush() called with VIDEO_EP_ALL, unsupported by most drivers

[josuah]

Describe the bug

The video API calls video_flush() from video_stream_stop() with ep=VIDEO_EP_ALL to flush all endpoints before stopping the stream.

Currently, most "data mover" drivers (not the sensors but MIPI/DVP ones) only filter VIDEO_EP_OUT
https://github.com/zephyrproject-rtos/zephyr/blob/main/include/zephyr/drivers/video.h#L456

Expected behavior

Calling video_stream_stop() succeeds on all video drivers supporting it.

Impact

The flush operation would fail upon calling video_stream_stop() for affected drivers.

Environment (please complete the following information):

• OS: (e.g. Linux, MacOS, Windows)
• Toolchain (e.g Zephyr SDK, ...)
• Commit SHA or Version used

Additional context

if (ep != VIDEO_EP_OUT) would need to be converted to if (ep != VIDEO_EP_OUT && ep != VIDEO_EP_ALL).
A PR with macros integrating this will be opened.