drivers/video: Update unlink() and video_uninitialize() operation

[SPRESENSE]

Summary

Add unregister_driver() execution to unlink() operation to delete device file.
Also, add resource cleanup to video_uninitialize() operation to avoid memory leak without unlink() execution for compatibility.

Impact

drivers/video

Testing

Tested with spresense

[SPRESENSE]

@xiaoxiang781216 Yes, it's as you say.
video_unregister() should free resource,
and video_uninitialize()/video_unlink() might be necessary to call video_unregister.

[xiaoxiang781216]

@xiaoxiang781216 Yes, it's as you say. video_unregister() should free resource, and video_uninitialize()/video_unlink() might be necessary to call video_unregister.

so we should move the change to video_unregister.

[SPRESENSE]

@xiaoxiang781216 I moved resource release from video_uninitialize() to video_unregister().

[xiaoxiang781216]

unregister_driver will call nx_unlink internally, why do we need make this change? @SPRESENSE

[SPRESENSE]

@xiaoxiang781216 When unregister_driver is executed, the device file is removed, but video_unlink() does not seem to be called.
(This was confirmed with my Spresense environment.)

So, this change is necessary to avoid memory leak.

[xiaoxiang781216]

Ok, after compare the mainline with our local git, I found @Donny9 hit the similar issue when dealing with USB hotplug, and change unreigster_driver to fix the problem.
unreigster_driver is better place to fix this issue. @Donny9 could you upstream the patch? so @SPRESENSE could verify whether your change work in this case too.

[Donny9]

@SPRESENSE please refs to #11892

[SPRESENSE]

@xiaoxiang781216 @Donny9 Thank you for information. I verified that work well with #11892 without my change. I withdraw this PR.

[xiaoxiang781216]

Ok, let me close this pr.