xfrm: Allow IPsec GSO with software crypto for local sockets.

With support of async crypto operations in the GSO codepath
we have everything in place to allow GSO for local sockets.
This patch enables the GSO codepath.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

include/net/xfrm.h

@@ -1910,6 +1910,8 @@ static inline bool xfrm_dst_offload_ok(struct dst_entry *dst)
 		return false;
 
 	xdst = (struct xfrm_dst *) dst;
+	if (!x->xso.offload_handle && !xdst->child->xfrm)
+		return true;
 	if (x->xso.offload_handle && (x->xso.dev == xfrm_dst_path(dst)->dev) &&
 	    !xdst->child->xfrm)
 		return true;