netfilter: nf_conncount: fix wrong variable type

[ Upstream commit 0b88d1654d556264bcd24a9cb6383f0888e30131 ]

Now there is a issue is that code checks reports a warning: implicit
narrowing conversion from type 'unsigned int' to small type 'u8' (the
'keylen' variable). Fix it by removing the 'keylen' variable.

Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>