RDS: mark few internal functions static to make sparse build happy

Fixes below warnings:
warning: symbol 'rds_send_probe' was not declared. Should it be static?
warning: symbol 'rds_send_ping' was not declared. Should it be static?
warning: symbol 'rds_tcp_accept_one_path' was not declared. Should it be static?
warning: symbol 'rds_walk_conn_path_info' was not declared. Should it be static?
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>

net/rds/connection.c

@@ -545,7 +545,7 @@ void rds_for_each_conn_info(struct socket *sock, unsigned int len,
 }
 EXPORT_SYMBOL_GPL(rds_for_each_conn_info);
 
-void rds_walk_conn_path_info(struct socket *sock, unsigned int len,
+static void rds_walk_conn_path_info(struct socket *sock, unsigned int len,
 				    struct rds_info_iterator *iter,
 				    struct rds_info_lengths *lens,
 				    int (*visitor)(struct rds_conn_path *, void *),

net/rds/send.c

@@ -1169,7 +1169,7 @@ int rds_sendmsg(struct socket *sock, struct msghdr *msg, size_t payload_len)
  * or
  *   RDS_FLAG_HB_PONG|RDS_FLAG_ACK_REQUIRED
  */
-int
+static int
 rds_send_probe(struct rds_conn_path *cp, __be16 sport,
 	       __be16 dport, u8 h_flags)
 {
@@ -1238,7 +1238,7 @@ rds_send_pong(struct rds_conn_path *cp, __be16 dport)
 	return rds_send_probe(cp, 0, dport, 0);
 }
 
-void
+static void
 rds_send_ping(struct rds_connection *conn)
 {
 	unsigned long flags;

net/rds/tcp_listen.c

@@ -79,6 +79,7 @@ int rds_tcp_keepalive(struct socket *sock)
  * smaller ip address, we recycle conns in RDS_CONN_ERROR on the passive side
  * by moving them to CONNECTING in this function.
  */
+static
 struct rds_tcp_connection *rds_tcp_accept_one_path(struct rds_connection *conn)
 {
 	int i;