[SCTP]: Cleanups

This patch contains the following cleanups:
- make the following needlessly global function static:
  - socket.c: sctp_apply_peer_addr_params()
- add proper prototypes for the several global functions in
  include/net/sctp/sctp.h

Note that this fixes wrong prototypes for the following functions:
- sctp_snmp_proc_exit()
- sctp_eps_proc_exit()
- sctp_assocs_proc_exit()

The latter was spotted by the GNU C compiler and reported
by David Woodhouse.

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Acked-by: Sridhar Samudrala <sri@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>