Bug 14076: Do not use CGI->param in list context - opac-authorities-home.pl

Bug 14076: Do not use CGI->param in list context - opac-authorities-home.pl

See bug 15809 for more info on why we should not use CGI->param in list
context.

Note: I have not found any places where several values for the same
params are passed to this script but, just in case, this patch won't
change this ability.

Test plan:
Do an authority search at the OPAC
Test with several values of the form.
Confirm that the results are always the same before and after this
patch.

Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Brendan Gallagher brendan@bywatersolutions.com
(cherry picked from commit 3fa2b10150a9ea2db2897be1246cba3785c55e55)
Signed-off-by: Julian Maurice <julian.maurice@biblibre.com>