net: sctp: sctp_ssnmap: remove 'malloced' element from struct

sctp_ssnmap_init() can only be called from sctp_ssnmap_new()
where malloced is always set to 1. Thus, when we call
sctp_ssnmap_free() the test for map->malloced evaluates always
to true.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>