zsh: trafgen: Add new command line option -A/--no-sock-mem

Commit 76486ece10c6 ("trafgen: add option to not adjust system socket
mem during testrun") introduced the new command line option
-A/--no-sock-mem for trafgen but didn't add it to the zsh completion. Do
it now.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>