No, I don't think that Brian Cranston is being type cast as a drug dealer. He is not even playing a drug dealer in The Infiltrator, but undercover U.S. Customs agent that is trying to infiltrate Pablo Escobar's cartel. And even if he was playing a drug dealer in this movie, that would be his second role as a drug dealer with powerful performance in Trumbo in between them.
One movie and one tv show is not an example of typecasting. While Breaking Bad is his best known role to date, that does not mean it is the only role he will ever play. Time will tell if he ends up being typecasted because of this iconic role he played.
I don't think that Bryan Cranston is being typecast since he's playing a drug dealer again in the film The Infiltrator. However, I think he'll be great in this role, just like he was in Breaking Bad. Cranston is one of the most talented actors of our day. He's played plenty of other types of roles in his career, and I think he can play anything!
As of now, I'd say not. He's best known for Breaking Bad, and for being a drug cooker and dealer, but in the Infiltrator, he's a federal agent who goes undercover, so that;s not exactly the same as far as character goes. If his next several projects are drug-related, then maybe he's being typecast.