netfilter: nft_payload: do not truncate csum_offset and csum_type

[ Upstream commit 7044ab28 ]

Instead report ERANGE if csum_offset is too long, and EOPNOTSUPP if type
is not support.

Fixes: 7ec3f7b4 ("netfilter: nft_payload: add packet mangling support")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>