A Hollywood Hills property Bono 's invested in was visited by first responders Thursday ... after authorities received a call about an alleged stabbing, TMZ has learned. The Los Angeles Police Department tells TMZ officers responded to the stabbing report around 1:20 PM PT, and they immediately started investigating the claim. The Los Angeles Fire Department tells TMZ they dispatched one fire engine and one ambulance to the house for an unconfirmed but reported stabbing ... and, we've obtained