lsm: replace the name field with a pointer to the lsm_id struct

Reduce the duplication between the lsm_id struct and the DEFINE_LSM()
definition by linking the lsm_id struct directly into the individual
LSM's DEFINE_LSM() instance.

Linking the lsm_id into the LSM definition also allows us to simplify
the security_add_hooks() function by removing the code which populates
the lsm_idlist[] array and moving it into the normal LSM startup code
where the LSM list is parsed and the individual LSMs are enabled,
making for a cleaner implementation with less overhead at boot.

Reviewed-by: Kees Cook <kees@kernel.org>
Reviewed-by: John Johansen <john.johansen@canonical.com>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

security/selinux/hooks.c

@@ -7639,7 +7639,7 @@ void selinux_complete_init(void)
 /* SELinux requires early initialization in order to label
    all processes and objects when they are created. */
 DEFINE_LSM(selinux) = {
-	.name = "selinux",
+	.id = &selinux_lsmid,
 	.flags = LSM_FLAG_LEGACY_MAJOR | LSM_FLAG_EXCLUSIVE,
 	.enabled = &selinux_enabled_boot,
 	.blobs = &selinux_blob_sizes,