RSDP is not mandatory according to PVH spec. Remove the BUG_ON. The
guest (xen) will fall back to scanning if necessary.
Reported-by: Andrew Cooper <andrew.cooper3@citrix.com> Signed-off-by: Wei Liu <wei.liu2@citrix.com> Reviewed-by: Andrew Cooper <andrew.cooepr3@citrix.com> Release-acked-by: Juergen Gross <jgross@suse.com>