Sparse warns us off:
drivers/xen/swiotlb-xen.c:506:1: warning: symbol 'xen_swiotlb_map_sg' was not declared. Should it be static?
drivers/xen/swiotlb-xen.c:534:1: warning: symbol 'xen_swiotlb_unmap_sg' was not declared. Should it be static?

and it looks like we do not need this function at all.
Acked-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>