libnl-tiny: correct license to GPLv2

pkgs/by-name/li/libnl-tiny/package.nix

···
   meta = with lib; {
     description = "Tiny OpenWrt fork of libnl";
     homepage = "https://git.openwrt.org/?p=project/libnl-tiny.git;a=summary";
-    license = licenses.isc;
+    license = licenses.gpl2Only;
     maintainers = with maintainers; [ mkg20001 ];
     platforms = platforms.linux;
   };