Smack: Handle CGROUP2 in the same way that CGROUP

The new file system CGROUP2 isn't actually handled
by smack. This changes makes Smack treat equally
CGROUP and CGROUP2 items.
Signed-off-by: NJosé Bollo <jose.bollo@iot.bzh>
Signed-off-by: NCasey Schaufler <casey@schaufler-ca.com>

security/smack/smack_lsm.c

@@ -3431,6 +3431,7 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode)
 	if (opt_dentry->d_parent == opt_dentry) {
 		switch (sbp->s_magic) {
 		case CGROUP_SUPER_MAGIC:
+		case CGROUP2_SUPER_MAGIC:
 			/*
 			 * The cgroup filesystem is never mounted,
 			 * so there's no opportunity to set the mount
@@ -3474,6 +3475,7 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode)
 	switch (sbp->s_magic) {
 	case SMACK_MAGIC:
 	case CGROUP_SUPER_MAGIC:
+	case CGROUP2_SUPER_MAGIC:
 		/*
 		 * Casey says that it's a little embarrassing
 		 * that the smack file system doesn't do