osc: fix crash when toggling visibility

The previous osc.lua related commit removed this function, and trying to
call it crashed the OSC. Just remove the call.

player/lua/osc.lua

@@ -2118,7 +2118,6 @@ function hide_osc()
         -- typically hide happens at render() from tick(), but now tick() is
         -- no-op and won't render again to remove the osc, so do that manually.
         state.osc_visible = false
-        timer_stop()
         render_wipe()
     elseif (user_opts.fadeduration > 0) then
         if not(state.osc_visible == false) then