net: remove duplicate sk_lookup helpers

Now that inet[6]_lookup_reuseport are parameterised on the ehashfn
we can remove two sk_lookup helpers.

Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Lorenz Bauer <lmb@isovalent.com>
Link: https://lore.kernel.org/r/20230720-so-reuseport-v6-6-7021b683cdae@isovalent.com


Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>