VSOCK: Make transport API consistent

Fix the names of the transport API so that they're a bit more consistent.
Also, remove the version IOCTL.

Acked-by: Dmitry Torokhov <dtor@vmware.com>
Acked-by: George Zhang <georgezhang@vmware.com>
Signed-off-by: Andy King <acking@vmware.com>
VSOCK: Move transport fields part 1

This is the first part of a change to move the transport fields out of the
common socket structure.  Wrap access to the fields in a macro, in preparation
for the next part which will allocate it in the transport itself.

Acked-by: Dmitry Torokhov <dtor@vmware.com>
Signed-off-by: Andy King <acking@vmware.com>