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/hpfs/namei.c

@@ -398,7 +398,7 @@ again:
 			hpfs_unlock(dir->i_sb);
 			return -ENOSPC;
 		}
-		if (generic_permission(inode, MAY_WRITE, 0, NULL) ||
+		if (generic_permission(inode, MAY_WRITE, 0) ||
 		    !S_ISREG(inode->i_mode) ||
 		    get_write_access(inode)) {
 			d_rehash(dentry);