dump: don't fail if multi-file dumps don't all contain quota info

dump: don't fail if multi-file dumps don't all contain quota info

When xfsdump is making multi-file dumps, the quota information are
written into the last dump file.  However, the multi-file restore script
(as written) expects to see quota information restored by every dump
file and fails.  This is silly, so fix it.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>