RDS: IB: Remove unused declarations

Commit f4f943c958a2 ("RDS: IB: ack more receive completions to improve performance")
removed rds_ib_recv_tasklet_fn() implementation but not the declaration.
And commit ec16227e1414 ("RDS/IB: Infiniband transport") declared but never implemented
other functions.

Signed-off-by: Yue Haibing <[e-mail]>
Reviewed-by: Simon Horman <[e-mail]>
Reviewed-by: Allison Henderson <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

net/rds/ib.h

···
 void rds_ib_conn_free(void *arg);
 int rds_ib_conn_path_connect(struct rds_conn_path *cp);
 void rds_ib_conn_path_shutdown(struct rds_conn_path *cp);
-void rds_ib_state_change(struct sock *sk);
-int rds_ib_listen_init(void);
-void rds_ib_listen_stop(void);
 __printf(2, 3)
 void __rds_ib_conn_error(struct rds_connection *conn, const char *, ...);
 int rds_ib_cm_handle_connect(struct rdma_cm_id *cm_id,
···
 int rds_ib_inc_copy_to_user(struct rds_incoming *inc, struct iov_iter *to);
 void rds_ib_recv_cqe_handler(struct rds_ib_connection *ic, struct ib_wc *wc,
 			     struct rds_ib_ack_state *state);
-void rds_ib_recv_tasklet_fn(unsigned long data);
 void rds_ib_recv_init_ring(struct rds_ib_connection *ic);
 void rds_ib_recv_clear_ring(struct rds_ib_connection *ic);
 void rds_ib_recv_init_ack(struct rds_ib_connection *ic);