gluon-autoupdater: use the new get_model function

package/gluon-autoupdater/files/usr/sbin/autoupdater

@@ -37,7 +37,8 @@ cleanup() {
 
 trap cleanup INT TERM EXIT PIPE
 
-my_model="$(cat /tmp/sysinfo/model | sed 's/ /-/g' | tr '[A-Z]' '[a-z]')"
+. /lib/gluon/functions/model.sh
+my_model="$(get_model | tr '[A-Z]' '[a-z]' | sed -r 's/[^a-z0-9]+/-/g')"
 
 if [ ! -f "$VERSION_FILE" ]; then
   echo "Couldn't determine firmware version!" >&2