[CIFS] drop quota operation stubs

CIFS has stubs for XFS-style quotas without an actual implementation backing
them, hidden behind a config option not visible in Kconfig.  Remove these
stubs for now as the quota operations will see some major changes and this
code simply gets in the way.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jeff Layton <jlayton@samba.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Steve French <sfrench@us.ibm.com>