INGLEWOOD, Calif.—Justin Herbert and the Los Angeles Chargers came into their showdown against the Las Vegas Raiders after a signature win on the road at Kansas City. In front of a prime-time audience on Monday night, the Chargers showed they are indeed for real. Herbert threw for three touchdowns, Austin Ekeler rushed for a career-high 117 yards and scored twice as the Chargers knocked the Raiders from the unbeaten ranks with a 28-14 victory. Los Angeles is 3-1 for the first time since 2014 and part of a three-way tie atop the AFC West with Las Vegas and Denver. The Raiders’ loss means the Arizona Cardinals are the NFL’s lone undefeated team after four weeks. “We stayed patient, I thought we had a good mix of the run and pass. Justin was extremely patient and Austin came alive tonight,” Chargers first-year coach Brandon Staley said. Herbert accounted for all of …