A lengthy piece about JPMorgan CEO Jamie Dimon in the new Vanity Fair includes this interesting tidbit. It seems that on July 13 — after a rough couple of months during which the firm lost $6 billion — Dimon got an unexpected phone call from a certain Super Bowl champ. Pats quarterback Tom Brady rang up the embattled executive — the call was arranged by JPM vice chairman James “Jimmy’’ Lee — with a few words of encouragement. The QB told Dimon to “hang in there,’’ according to the piece. Dimon’s reaction? “I was surprised he even knew who I was, to tell you the truth,’’ he said.