Prince and 3RDEYEGIRL played a surprise two-hour show in London on Monday night. The private show, in support of the charity Autism Rocks, included 34 songs including “When Doves Cry,” “1999,” “Little Red Corvette,” “FUNKNROLL,” and “U KNOW.” (NME) Now, will he show up at the Grammys on Sunday—and if so, what will he do? No one…