Tom Brady owes a lot of his success to Tom Martinez, the 68-year-old QB coach from California who’s mentored No. 12 since he was a boy. So it’s no surprise that the star pupil is trying to help his teacher, who’s in failing health and needs a kidney transplant. “Tom’s a great guy and has given us great visibility,’’ says Paul Dooley, CEO of Canton-based MatchingDonors.com, which is trying to find a kidney for Martinez. CBS aired a segment on Martinez and Brady on Thanksgiving Day, and afterward several potential donors stepped forward. Alas, none was a match for Martinez. “It’s OK. If they’re not a match for Tom, they might be a match for someone else,’’ said Dooley. In case you’re wondering, Martinez last tutored Brady during a practice at Gillette Stadium in September. Ever since, the coach has not been well enough to travel.