Vikings defensive end Brian Robison will have surgery on a varicose vein in his left leg.  The team says he will be out indefinitely.  Robison hasn’t practiced since Monday, but earlier indicated that it’s a minor problem that will probably sideline him for two or three weeks.  Coach Brad Childress thinks Robison will be back at camp by Monday to undergo rehab, but likely won’t participate in any practices for some time.  The Vikings open up preseason play with a game against the Seahawks tomorrow.