Add status changing and feature negotiation.
Add basic virtqueue support for adding and sending virtqueue requests.
Add ISR checking.
[Squashed request endianness fix by Greg Kurz <gkurz@linux.vnet.ibm.com>
--Stefan]
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Marc Marí <marc.mari.barcelo@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>