Don't notify virtio devices before S_DRIVER_OK (Mark McLoughlin)

Current Linux guests oops if the host notifies of a
config change before a driver has been bound to the
device.

It's pretty pointless for us to do notify of config
changes before status is S_DRIVER_OK anyway, so let's
just not do it.

Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6471 c046a42c-6fe2-441c-8c8c-71466251a162
