bbctl: add waterfall mode to signal command
bbctl: add waterfall mode to signal command

Reported-by: Hans Peter Mortense <d87d2943ff8055ff4c9c09951b9f1059a694f7e8@gmail.com>
Tested-by: Hans Peter Mortense <d87d2943ff8055ff4c9c09951b9f1059a694f7e8@gmail.com>
Signed-off-by: Jeppe Ledet-Pedersen <15dc315eb688d5391231b93ed828e3333b4726fa@satlab.org>

satlab/bbctl,aausat/bbctl,satlab/bbctl,satlab/bbctl,satlab/bbctl,aausat/bbctl