xfs: don't repair fs summary counters with garbage

LOLLM noticed that if we scan the filesystem and come up with totally
garbage numbers for the summary counters, we don't actually mark the
scan incomplete.  Because we don't do this, repair can install the
garbage values into the filesystem, making things worse.  Don't do that.

Cc: <stable@vger.kernel.org> # v6.9
Fixes: 4ed080cd7cb077 ("xfs: repair summary counters")
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Assisted-by: LOLLM # finding obvious bugs