smack: Remove the redundant lsm_inode_alloc

It's not possible for inode->i_security to be NULL here because every
inode will call inode_init_always and then lsm_inode_alloc to alloc
memory for inode->security, this is what LSM infrastructure management
do, so remove this redundant code.
Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>

security/smack/smack_lsm.c

@@ -766,13 +766,6 @@ static int smack_set_mnt_opts(struct super_block *sb,
 	if (sp->smk_flags & SMK_SB_INITIALIZED)
 		return 0;
 
-	if (inode->i_security == NULL) {
-		int rc = lsm_inode_alloc(inode);
-
-		if (rc)
-			return rc;
-	}
-
 	if (!smack_privileged(CAP_MAC_ADMIN)) {
 		/*
 		 * Unprivileged mounts don't get to specify Smack values.