Bug 38272: Add permission check for erm permission to additional-fields.tt

Bug 38272: Add permission check for erm permission to additional-fields.tt

To test:

1) Create a user with just erm and catalogue permissions.
2) Open additional-fields.pl
3) Notice that nothing is displayed
4) Change the permission of the user to just manage aquisition orders and catalogue
5) Navigate back to additional-fields.pl
6) Notice that nothing is displayed
7) Apply patch
8) Repeat 1-6 but notice this time that the respective entries are displayed
9) Sign off

Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>