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 92483fe11b
(semantically).

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

app/src/scrcpy.c

@@ -448,9 +448,7 @@ scrcpy(struct scrcpy_options *options) {
 
     struct sc_file_pusher *fp = NULL;
 
-    // control implies video playback
-    assert(!options->control || options->video_playback);
-    if (options->control) {
+    if (options->video_playback && options->control) {
         if (!sc_file_pusher_init(&s->file_pusher, serial,
                                  options->push_target)) {
             goto end;