ocfs2: Don't use MAXQUOTAS value

MAXQUOTAS value defines maximum number of quota types VFS supports.
This isn't necessarily the number of types ocfs2 supports and with
addition of project quotas these two numbers stop matching. So make
ocfs2 use its private definition.

CC: Mark Fasheh <mfasheh@suse.com>
CC: Joel Becker <jlbec@evilplan.org>
CC: ocfs2-devel@oss.oracle.com
Signed-off-by: Jan Kara <jack@suse.cz>