Depends on the situation.
In NYC, you'll get sued, and if they believe you acted recklessly (i.e. no warrant, no reason, no just cause, nada), you'll lose your badge and the city may refuse to give you legal immunity to protect you from prosecution.
In other cases, the cops are simply told "bad boy" and allowed to walk.
It all depends on why they broke into the wrong place.
If it was because someone misread a warrant and got the wrong address, then that cop could face prosecution and will almost certainly lose his badge.
"Sued" or "bad boy" is a lot different from being arrested.