* whisper: remove whisper

* Update cmd/geth/config.go
Co-authored-by: Marius van der Wijden <m.vanderwijden@live.de>

* cmd/geth: warn on enabling whisper + remove more whisper deps

* mobile: remove all whisper references
Co-authored-by: Marius van der Wijden <m.vanderwijden@live.de>
Co-authored-by: Martin Holst Swende <martin@swende.se>