relax: Fix RelaxNG definition for vf_fallback_mode
relax: Fix RelaxNG definition for vf_fallback_mode

Signed-off-by: Steve Hodgson <eb20a6615749cf04ff61aa37e18f749ed6d01446@solarflare.com>
(cherry picked from commit e3fba125c2a886796e496684464e674c1fc55de7)

sshah-solarflare/Libvirt-PCI-passthrough-,sshah-solarflare/Libvirt-PCI-passthrough-,sshah-solarflare/Libvirt-PCI-passthrough-,sshah-solarflare/Libvirt-PCI-passthrough-,sshah-solarflare/Libvirt-PCI-passthrough-