gfs2: Set allowed quota types

We support user and group quotas. Tell vfs about it.

Acked-by: Steven Whitehouse <swhiteho@redhat.com>
CC: cluster-devel@redhat.com
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>