Revert "iptables: update to 1.8.4"

Revert "iptables: update to 1.8.4"

This reverts commit 10cbc896c0a26aecff37261450c21f29fb5b99db.

The updated iptables package does not build due to the following error
encountered on the buildbots:

    cp: cannot stat '.../iptables-1.8.4/ipkg-install/usr/lib/libiptc.so.*': No such file or directory

The changelog mentions "build: remove -Wl,--no-as-needed and libiptc.so" so
it appears as if further packaging changes are needed beyond a simple
version bump.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>