ClatdController - iptables drop including interface name

This is a very minor bug fix.  Technically we could have duplicate
src/dst ip's on different interfaces and then we'd end up with the second
add failing and the first remove succeeding and there being nothing left
for the second remove...

Test: atest bpf_module_test clatd_test libbpf_android_test libnetdbpf_test
  netd_integration_test netd_unit_test netdutils_test resolv_integration_test
  resolv_unit_test
Related-Bug: 136696213
Bug: 65674744
Bug: 79546774
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I76a4b8de70e9d9df1e17bd7fb7461b3ec9eb898b