netfilter: Fix fall-through warnings for Clang

netfilter: Fix fall-through warnings for Clang

[ Upstream commit c2168e6bd7ec50cedb69b3be1ba6146e28893c69 ]

In preparation to enable -Wimplicit-fallthrough for Clang, fix multiple
warnings by explicitly adding multiple break statements instead of just
letting the code fall through to the next case.

Link: https://github.com/KSPP/linux/issues/115
Acked-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>