nfs4: allow nfsv4 acls on non-regular-files

The rfc doesn't give any reason it shouldn't be possible to set an
attribute on a non-regular file.  And if the server supports it, then it
shouldn't be up to us to prevent it.

Thanks to Erez for the report and Trond for further analysis.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Tested-by: Erez Zadok <ezk@cs.sunysb.edu>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/nfs4proc.c

@@ -3617,10 +3617,6 @@ int nfs4_setxattr(struct dentry *dentry, const char *key, const void *buf,
 	if (strcmp(key, XATTR_NAME_NFSV4_ACL) != 0)
 		return -EOPNOTSUPP;
 
-	if (!S_ISREG(inode->i_mode) &&
-	    (!S_ISDIR(inode->i_mode) || inode->i_mode & S_ISVTX))
-		return -EPERM;
-
 	return nfs4_proc_set_acl(inode, buf, buflen);
 }