bpfcountd: remove incomplete/broken namespace feature

bpfcountd: remove incomplete/broken namespace feature

The original idea of the extra namespace variable was to set up
bpfcountd from other daemons etc. independent of what a user configured
in /etc/config/bpfcountd for instance. Like:

 $ UCI_CONFIG_DIR=/var/run/bpfcountd/gluon-config \
   /etc/init.d/bpfcountd start "" gluon

However there are still issues with this approach:

1) Instance specific stop calls like:

 $ /etc/init.d/bpfcountd stop <instance-name> <namespace>"

will not  stop the according namespaced instance, as the stop() in
/etc/rc.common will call procd_kill() without the namespace prefix.
And we can't overwrite that behaviour. And asking a user to use
"... start <in> <ns>" and "... stop <ns>.<in>" is confusing.
(and currently "... stop <ns>.<in>" would not remove the correct
unix socket).

2) A stop call without an instance/config name would always stop all
instances. So the namespace variable would be ignored.
While start without an instance "works", but:

3) It would stop any process that is not in the currently selected
UCI_CONFIG_DIR.

As all this is not easily fixable without changing OpenWrt internals,
just remove the whole namespace idea for now.

Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>