reiserfs: Don't use MAXQUOTAS value

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

CC: reiserfs-devel@vger.kernel.org
CC: Jeff Mahoney <jeffm@suse.de>
Signed-off-by: Jan Kara <jack@suse.cz>