Check bmx7 was installed

src/freedombone-image-mesh

     systemctl disable bmx6
     echo $'BMX6 disabled' >> $INSTALL_LOG
 
-    systemctl stop bmx7
-    systemctl disable bmx7
-    echo $'BMX7 disabled' >> $INSTALL_LOG
+    if [ -d /etc/bmx7 ]; then
+        systemctl stop bmx7
+        systemctl disable bmx7
+        echo $'BMX7 disabled' >> $INSTALL_LOG
+    fi
 
     systemctl stop olsr2
     systemctl disable olsr2