Lily Gladstone's not happy with the Super Bowl champs' name ... and she says the NFL runner-ups' mascot ain't much better. The actress and activist spoke during a Santa Barbara International Film Festival panel last weekend, before the Chiefs defeated the 49ers ... and ripped Chiefs fans' use of the tomahawk chop -- a hand gesture and chant used by fans of teams with Native American mascots. LG said the gesture is a reminder of what Hollywood has done to Native Americans ... pointing out the chant was used in old Westerns before indigenous actors were given the opportunity to...