- fix "nvram get"

  when value has an "=" "nvram get" had returned an emtpy value.
  e.g.: wireguard_secret=APZiy5Wp3G9XzHOLbREC4T3e9CrUXjwDj02QzyPsIns==
- convert wireguard_secret (if present)

salt/freifunk/base/uci/usr/local/bin/nvram-migration.sh

 #!/bin/sh
 
-nvram_get() { sed -n "/^$1=/{s#^.*=##;p}" /etc/nvram.conf | head -1 ; }
+nvram_get() { sed -n "/^$1=/{s#^[^=]*=##;p}" /etc/nvram.conf | head -1 ; }
 
 if [ -f /etc/nvram.conf ]; then
 
@@ -25,6 +25,8 @@ if [ -f /etc/nvram.conf ]; then
 	uci set ffdd.sys.fastd_public="$(nvram_get fastd_public)"
 	uci set ffdd.sys.fastd_restrict="$(nvram_get fastd_restrict)"
 
+    uci set ffdd.sys.wireguard_secret="$(nvram_get wireguard_secret)"
+    
 	uci set ffdd.sys.ssh_pwauth="$(nvram_get ssh_pwauth)"
 
 	uci set ffdd.sys.ifname="$(nvram_get ifname)"