kvmvapic: fix state change handler

This patch fixes kvmvapic state change handler.
It clears vmsentry field to allow recreating it
at further vmstate loads.

Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
Message-Id: <20160915090127.6440.48793.stgit@PASHA-ISP>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

hw/i386/kvmvapic.c

@@ -768,6 +768,7 @@ static void kvmvapic_vm_state_change(void *opaque, int running,
     }
 
     qemu_del_vm_change_state_handler(s->vmsentry);
+    s->vmsentry = NULL;
 }
 
 static int vapic_post_load(void *opaque, int version_id)