sctp: remove sctp_assoc_proc_exit()

Commit 20c2c1fd
(sctp: add sctp/remaddr table to complete RFC remote address table OID)
added an unused sctp_assoc_proc_exit() function that seems to have been 
unintentionally created when copying the assocs code.

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>