MAINTAINERS: s/Marcelo/Paolo/

Marcelo doesn't maintain kvm anymore,
Paolo is taking over the job.
Update MAINTAINERS to stop flooding Marcelo with mail.
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

MAINTAINERS

@@ -155,7 +155,7 @@ Guest CPU Cores (KVM):
 
 Overall
 M: Gleb Natapov <gleb@redhat.com>
-M: Marcelo Tosatti <mtosatti@redhat.com>
+M: Paolo Bonzini <pbonzini@redhat.com>
 L: kvm@vger.kernel.org
 S: Supported
 F: kvm-*