MAINTAINERS: drop an out of date address

Gleb's address seems to be out of date.  Since it stayed like that for a
while now, I'm guessing he's no longer interested in getting mail.
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

MAINTAINERS

@@ -158,7 +158,6 @@ Guest CPU Cores (KVM):
 ----------------------
 
 Overall
-M: Gleb Natapov <gleb@redhat.com>
 M: Paolo Bonzini <pbonzini@redhat.com>
 L: kvm@vger.kernel.org
 S: Supported
@@ -181,7 +180,6 @@ S: Maintained
 F: target-s390x/kvm.c
 
 X86
-M: Gleb Natapov <gleb@redhat.com>
 M: Marcelo Tosatti <mtosatti@redhat.com>
 L: kvm@vger.kernel.org
 S: Supported