bpf: net: netfilter: drop dead NULL checks

bpf: net: netfilter: drop dead NULL checks

bpf_xdp_ct_lookup() and bpf_skb_ct_lookup() receive bpf_tuple and opts
parameter that are expected to be not NULL for real usages (see doc
string above functions). They return an error if NULL is passed for opts
or tuple.

The verifier will now reject programs that pass NULL to these
parameters, the kfuns can assume that these are always valid pointer, so
drop the NULL checks for these parameters.

Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Link: https://lore.kernel.org/r/20260102180038.2708325-4-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>