e1000: don't raise interrupt in pre_save()

We should not raise any interrupt after VM has been stopped but this
is what e1000 currently did when mit timer is active in
pre_save(). Fixing this by scheduling a timer in post_load() which can
make sure the interrupt was raised when VM is running.

Reported-and-tested-by: Longpeng <longpeng2@huawei.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

hw/net/e1000.c

@@ -1381,11 +1381,6 @@ static int e1000_pre_save(void *opaque)
     E1000State *s = opaque;
     NetClientState *nc = qemu_get_queue(s->nic);
 
-    /* If the mitigation timer is active, emulate a timeout now. */
-    if (s->mit_timer_on) {
-        e1000_mit_timer(s);
-    }
-
     /*
      * If link is down and auto-negotiation is supported and ongoing,
      * complete auto-negotiation immediately. This allows us to look
@@ -1423,7 +1418,8 @@ static int e1000_post_load(void *opaque, int version_id)
         s->mit_irq_level = false;
     }
     s->mit_ide = 0;
-    s->mit_timer_on = false;
+    s->mit_timer_on = true;
+    timer_mod(s->mit_timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + 1);
 
     /* nc.link_down can't be migrated, so infer link_down according
      * to link status bit in mac_reg[STATUS].