If you call it like this:

my @files = getPlatformFiles($platform, $nic->{device});
[download]

your sub should look like this

sub getPlatformFiles {
  my $plat_in = shift;
  my $nic_device_in = shift;
  my @list;
  if ($plat_in =~ /RedHat/) {
    @list = ("/etc-test/resolv.conf",
             "/etc-test/sysconfig/network-scripts/ifcfg-$nic_device_in
+");
  }
  return @list;
}
[download]