Billy Corgan is embracing his “port wine” birthmark after trying to hide it his “whole life”. The Smashing Pumpkins frontman, 57, revealed the birthmark – which covers parts of his hand, wrist and arm – in a powerful social media post as he urged his fans to “find peace with who you are”. He wrote on Instagram: “I’m a fan of body positivity movements because at the end of the day it is about celebrating what makes us ‘us.’ ” He also shared a photo of “beautiful” model Carlotta Bertotti as an example of someone “with a birthmark who has embraced her ‘difference’ with grace”. He continued: “My p…