Incorrect error returned on setting file compressed on SMB2

When the server (for an SMB2 or SMB3 mount) doesn't support
an ioctl (such as setting the compressed flag
on a file) we were incorrectly returning EIO instead
of EOPNOTSUPP, this is confusing e.g. doing chattr +c to a file
on a non-btrfs Samba partition, now the error returned is more
intuitive to the user.  Also fixes error mapping on setting
hardlink to servers which don't support that.

Signed-off-by: Steve French <smfrench@gmail.com>
Reviewed-by: David Disseldorp <ddiss@suse.de>