Revert "virtio: don't call device on !vm_running"

This reverts commit a1bc7b827e422e1ff065640d8ec5347c4aadfcd8.
    virtio: don't call device on !vm_running
It turns out that virtio net assumes that vm_running
is updated before device status callback in many places,
so this change leads to asserts.
Previous commit fixes the root issue that motivated
a1bc7b827e422e1ff065640d8ec5347c4aadfcd8 differently,
so there's no longer a need for this change.

In the future, we might be able to drop checking vm_running
completely, and check vm state directly.

Reported-by: Dietmar Maurer <dietmar@proxmox.com>
Cc: qemu-stable@nongnu.org
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
