kill check_acl callback of generic_permission()

its value depends only on inode and does not change; we might as
well store it in ->i_op->check_acl and be done with that.

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

fs/nilfs2/inode.c

@@ -806,7 +806,7 @@ int nilfs_permission(struct inode *inode, int mask, unsigned int flags)
 	    root->cno != NILFS_CPTREE_CURRENT_CNO)
 		return -EROFS; /* snapshot is not writable */
 
-	return generic_permission(inode, mask, flags, NULL);
+	return generic_permission(inode, mask, flags);
 }
 
 int nilfs_load_inode_block(struct inode *inode, struct buffer_head **pbh)