Bug 25137: (bug 23084 follow-up) Fix incorrect grep ternary condition

Bug 25137: (bug 23084 follow-up) Fix incorrect grep ternary condition

The lack of parenthesis makes the condition evaluated wrong.

Test plan:
- confirm you have a branch with code X
- enter X in PatronSelfRegistrationLibraryList
- go to cgi-bin/koha/opac-memberentry.pl (either as a logged in patron or as a self-reg patron)
- confirm branch dropdown is not empty and contain X
- empty out PatronSelfRegistrationLibraryList
- reload cgi-bin/koha/opac-memberentry.pl and confirm branches show

Signed-off-by: Bernardo Gonzalez Kriegel <bgkriegel@gmail.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>