Prepare xen_be_send_notify to be shared with frontends:
 * xen_be_send_notify -> xen_pv_send_notify
Signed-off-by: NEmil Condrea <emilcondrea@gmail.com>
Signed-off-by: NStefano Stabellini <sstabellini@kernel.org>
Signed-off-by: NQuan Xu <xuquan8@huawei.com>
Acked-by: NAnthony PERARD <anthony.perard@citrix.com>