drivers: video: introduce CONFIG_VIDEO_LOG_LEVEL

Zephyr drivers have typically one log level defined per class. The video
drivers were making exception. This adds the missing log level for video
drivers.

Since all headers had to be modified, this also:

- Update the log initialization to the new syntax from 5e346812

- Sort the #include list to something like #41543

Signed-off-by: Josuah Demangeon <me@josuah.net>