Do not disable controls without video playback

Some control messages can still be used even when video playback is
disabled (i.e. there is no window), for example to turn the screen off.

This reverts commit 92483fe11b6fd6bae5ef775ccaff78fefa92aad4
(semantically).

Fixes #4175 <https://github.com/Genymobile/scrcpy/issues/4175>