Unbreak Wi-Fi on < Mk.8 (#8077)

Don't pass empty parameters to insmod, it apparently doesn't like it...

Fix #8075
Regression since a91ba05e34

platform/kobo/enable-wifi.sh

@@ -46,10 +46,18 @@ if ! grep -q "${WIFI_MODULE}" "/proc/modules"; then
     fi
 
     if [ -e "/drivers/${PLATFORM}/wifi/${WIFI_MODULE}.ko" ]; then
-        insmod "/drivers/${PLATFORM}/wifi/${WIFI_MODULE}.ko" "${WIFI_COUNTRY_CODE_PARM}"
+        if [ -n "${WIFI_COUNTRY_CODE_PARM}" ]; then
+            insmod "/drivers/${PLATFORM}/wifi/${WIFI_MODULE}.ko" "${WIFI_COUNTRY_CODE_PARM}"
+        else
+            insmod "/drivers/${PLATFORM}/wifi/${WIFI_MODULE}.ko"
+        fi
     elif [ -e "/drivers/${PLATFORM}/${WIFI_MODULE}.ko" ]; then
         # NOTE: Modules are unsorted on Mk. 8
-        insmod "/drivers/${PLATFORM}/${WIFI_MODULE}.ko" "${WIFI_COUNTRY_CODE_PARM}"
+        if [ -n "${WIFI_COUNTRY_CODE_PARM}" ]; then
+            insmod "/drivers/${PLATFORM}/${WIFI_MODULE}.ko" "${WIFI_COUNTRY_CODE_PARM}"
+        else
+            insmod "/drivers/${PLATFORM}/${WIFI_MODULE}.ko"
+        fi
     fi
 fi
 # Race-y as hell, don't try to optimize this!