corevideo: fix video initialization when not using VDA

query_format was setting state even if wasn't the correct thing to do. Somehow
it worked by pure luck (until commit e6e6b88b6da).

Fix the initialization by setting state inside of reconfig.
Revert "cocoa: unlock on uninit"

Not sure why but this doesn't seem to be needed anymore.

This reverts commit 6ead6aa005f1c78a117bde58e48f106cfd1e9806.