Bug 15172: (follow-up)Serial enumchron/sequence not visible when returning/checking...

Bug 15172: (follow-up)Serial enumchron/sequence not visible when returning/checking in Items

Display br and span tag only if the value enumchron exists.

To test
-Apply patches
-Follow the previous test plan
-Checkin whichever material (e.g., book) without sequence or enumchrom
-Open up source code for checkin page, search under title and
verify that b and span tags do not appear

Signed-off-by: Alain et Aurélie <aurelie.berut@enssib.fr>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>