He is suspended indefinitely thus he does not count against the cap.
The rule is, if a player is suspended then the cap number for said player is reduced by the number of games he is suspended. If a player has a four game suspension then his cap number is reduced by 1/4.
Thus Washington is currently suspended indefinitely, thus he is suspended for 16 out of 16 games, which mean he doesn't count against the cap.
Once he is re-instated, he will then again, count towards the cap.
That being said I COMPLETELY UNDERSTAND if you click on overthecap.com, there is Washington counting against the cap. Doesn't matter, he is suspended regardless.
I have stated all this many times, and if anyone doesn't take me at my word, I would advise you research online and you will find the same information I have.
Thus Washington being on the books doesn't count for anything until the bastard is re-instated, and that point I would expect the Cardinals to release him immediately.