Revert "firmware_nonfree is now a boolean"

This reverts commit 898604a772.

scripts/install

@@ -116,7 +116,7 @@ export DEBIAN_FRONTEND=noninteractive
 
 # Packaged USB Wireless Device firmwares
 # Based on https://wiki.debian.org/WiFi#USB_Devices
-if [[ $firmware_nonfree -eq 1 ]]; then
+if [[ $firmware_nonfree == yes ]]; then
   # check if non-free is set on sources.list
   if ! grep -q non-free /etc/apt/sources.list ; then
     sed '/debian/{s/main/& non-free/}' -i /etc/apt/sources.list

scripts/remove

@@ -60,7 +60,7 @@ do
 done
 
 # Remove packages
-if [[ $firmware_nonfree -eq 1 ]]; then
+if [[ $firmware_nonfree == yes ]]; then
   packages=$nonfree_packages
 else
   packages=$free_packages