Remove debugging info from protocol tree for frame

Change-Id: Id7f02087e536964bfa6d01a3646c20035a3ab6cb
Reviewed-on: https://code.wireshark.org/review/2746
Reviewed-by: Graham Bloice <graham.bloice@trihedral.com>
Tested-by: Graham Bloice <graham.bloice@trihedral.com>
Reviewed-by: Anders Broman <a.broman58@gmail.com>