MAINTAINERS: update KVM entry

Add myself to KVM MAINTAINERS entry.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

MAINTAINERS

@@ -2928,6 +2928,7 @@ F:	include/linux/sunrpc/
 
 KERNEL VIRTUAL MACHINE (KVM)
 M:	Avi Kivity <avi@redhat.com>
+M:	Marcelo Tosatti <mtosatti@redhat.com>
 L:	kvm@vger.kernel.org
 W:	http://kvm.qumranet.com
 S:	Supported