Revert "ebtables: use extrapositioned negation consistently"

Revert "ebtables: use extrapositioned negation consistently"

This reverts commit 5f508b76a0cebaf91965ffa678089222e2d47964.

While attempts at unifying syntax between arp-, eb- and iptables-nft
increase the opportunity for more code-sharing, they are problematic
when it comes to compatibility. Accepting the old syntax on input helps,
but due to the fact that neither arptables nor ebtables support --check
command we must expect for users to test existence of a rule by
comparing input with output. If that happens in a script, deviating from
the old syntax in output has a high chance of breaking it.

Therefore revert Florian's patch changing inversion character position
in output and review the old code for consistency - the only thing
changed on top of the actual revert is ebtables' own copy of
print_iface() to make it adhere to the intrapositioned negation scheme
used throughout ebtables.

Added extension tests by the reverted commit have been kept.

Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Florian Westphal <fw@strlen.de>