Bug 6007: Fix MARC framework display when only used tags/subfields

Bug 6007: Fix MARC framework display when only used tags/subfields

The "Display only used tags/subfields" output breaks DataTables and the
output is unusable.

Test plan:
1/ Go on admin/marctagstructure.pl after you have selected a framework
2/ Check the checkbox
3/ The table should be correctly displayed.
Before this patch, the table have 2 lines per tag, now all data are
contained into the same line.

Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>