switch nilfs2 to inode->i_acl

Actually, get rid of private analog, since nothing in there is
using ACLs at all so far.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/nilfs2/nilfs.h

@@ -57,10 +57,6 @@ struct nilfs_inode_info {
 	 * EAs.
 	 */
 	struct rw_semaphore xattr_sem;
-#endif
-#ifdef CONFIG_NILFS_POSIX_ACL
-	struct posix_acl *i_acl;
-	struct posix_acl *i_default_acl;
 #endif
 	struct buffer_head *i_bh;	/* i_bh contains a new or dirty
 					   disk inode */