netfilter: ebtables: fix memory leak when blob is malformed

netfilter: ebtables: fix memory leak when blob is malformed

[ Upstream commit 73383c1f40e290c4681d425db8ca30f44f7f05e2 ]

The bug fix was incomplete, it "replaced" crash with a memory leak.
The old code had an assignment to "ret" embedded into the conditional,
restore this.

Fixes: d3dd6af1d116 ("netfilter: ebtables: reject blobs that don't provide all entry points")
Reported-and-tested-by: syzbot+a24c5252f3e3ab733464@syzkaller.appspotmail.com
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>