Revert "clipboard-wayland: flush display after creating data sources"

Not needed anymore. After data sources are created, the next loop
iteration of clipboard_wayland_dispatch_events will immediately start
and flush display.

This reverts commit c399422722.

player/clipboard/clipboard-wayland.c

@@ -301,7 +301,6 @@ static void create_data_sources(struct clipboard_wayland_priv *wl)
             seat_create_data_source(seat, true);
         }
     }
-    wl_display_flush(wl->display);
 }
 
 static void clipboard_wayland_uninit(struct clipboard_wayland_priv *wl)