Reduce number of notifications when setting camera lens via helpers

Change-Id: Ib028b2d971a4074e2b8b7dda2e4c779314f2b61e
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>
Improve the notification blocking efficiency

Change-Id: I67b6179e416cc2d099a1f05041161f5b0360e7db
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>