By Evan Bleier Following the surprise announcement that Dustin Johnson will be playing in next week’s Saudi-backed LIV Golf Invitational three months after declaring he was “fully committed” to the PGA Tour, the Royal Bank of Canada has dropped the world’s 13th-ranked player as an endorser. Golfer Graeme McDowell was also cut by the RBC. Johnson, who had made a bit more than $1.6 million on the Tour this season, was one of 42 players who were announced on Tuesday as being part of the 48-man, 12-team event in London on June 9-11. Phil Mickelson, who many assumed would be part of the event given…