kaleidoscope::device::Base: Don't make the default noop_serial_ static

With `noop_serial_` being static, if we don't override the `serial()` method, we
fail to link.

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

src/kaleidoscope/device/Base.h

@@ -90,7 +90,7 @@ class Base {
     }
   };
 
-  static NoOpSerial noop_serial_;
+  NoOpSerial noop_serial_;
 
  public:
   Base() {}