Remove todo from the benchmark application

[RonEld]

Remove the todo struct from the benchmark application, as it is a legacy from the origin of the example

[ciarmcom]

ARM Internal Ref: IOTSSL-2420

[andresag01]

@sbutcher-arm, @RonEld: I think this was fixed by #194. Should we close this issue

[andresag01]

This was fixed via #194, so it can now be closed.