FocusSerial: Only send a single separator when sending Keys

When sending `Key`s, there's no need for an extra separator, because
`send(key.raw)` will send one anyway. Not sending one results in 10 bytes less
PROGMEM used, and plenty of bytes less spent over the wire.

Signed-off-by: Gergely Nagy <algernon@keyboard.io>

src/kaleidoscope/plugin/FocusSerial.h

@@ -34,7 +34,6 @@ class FocusSerial : public kaleidoscope::Plugin {
   }
   void send(const Key key) {
     send(key.raw);
-    Serial.print(SEPARATOR);
   }
   void send(const bool b) {
     printBool(b);