Fixture Editor: fix commit 333bfa98: allow the name to stay the same as before

reported by cingulingu in https://sourceforge.net/p/qlcplus/discussion/development/thread/ef306f5c
Fix ADJ Sweeper Beam definition - RGB matrices don't work with White channels yet.

See https://sourceforge.net/p/qlcplus/discussion/general/thread/4b54ea6a