Robby Romero — the musician son of actress Rita Rogers who was mentored by Dennis Hopper as a teen — visited the “Easy Rider” star’s grave to perform a Native American ritual on the day of the Mayan apocalypse Friday. Romero was at the grave at sunrise in Ranchos de Taos, NM, we’re told, to give a “ceremonial tobacco offering.” (At Hopper’s request, his 2010 burial was a simple Native American ceremony, and Romero, of Apache descent, says he dug the grave.) Romero has also dedicated a new single, “Who’s Gonna Save You,” to Hopper and Rogers. It debuted on iTunes Friday, and Romero says the song will benefit eco-friendly initiative Project Protect.