Don't forget to init the VFP stuff for all cores.
Fix SMP build.
Export vfp_init() prototype, for use in the MP code.
Ignore the BARRIER flag in the virtio block header.

This capability is not advertised by the host so ignore it even if the guest
insists on setting the flag.

Reviewed by:	grehan
Obtained from:	NetApp
Fix casting.

MFC after:	3 days