smack: move initcalls to the LSM framework

smack: move initcalls to the LSM framework

As the LSM framework only supports one LSM initcall callback for each
initcall type, the init_smk_fs() and smack_nf_ip_init() functions were
wrapped with a new function, smack_initcall() that is registered with
the LSM framework.

Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: John Johansen <john.johhansen@canonical.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>