SUNRPC: Make the transport-specific setup routine allocate rpc_xprt

Change the location where the rpc_xprt structure is allocated so each
transport implementation can allocate a private area from the same
chunk of memory.

Note also that xprt->ops->destroy, rather than xprt_destroy, is now
responsible for freeing rpc_xprt when the transport is destroyed.

Test plan:
Connectathon.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
index 0321fb5..d791901 100644
--- a/include/linux/sunrpc/xprt.h
+++ b/include/linux/sunrpc/xprt.h
@@ -265,8 +265,8 @@
 /*
  * Socket transport setup operations
  */
-int			xs_setup_udp(struct rpc_xprt *xprt, struct rpc_timeout *to);
-int			xs_setup_tcp(struct rpc_xprt *xprt, struct rpc_timeout *to);
+struct rpc_xprt *	xs_setup_udp(struct sockaddr *addr, size_t addrlen, struct rpc_timeout *to);
+struct rpc_xprt *	xs_setup_tcp(struct sockaddr *addr, size_t addrlen, struct rpc_timeout *to);
 
 /*
  * Reserved bit positions in xprt->state