net, lib: kill arch_fast_hash library bits

net, lib: kill arch_fast_hash library bits

As there are now no remaining users of arch_fast_hash(), lets kill
it entirely.

This basically reverts commit 024dc738e624 ("lib: introduce arch
optimized hash library") and follow-up work, that is f.e., commit
23e7527e4196 ("lib: hash: follow-up fixups for arch hash"),
commit 58f0938f88b1 ("lib: Add missing arch generic-y entries for
asm-generic/hash.h") and last but not least commit 8e6e3661d918
("perf tools: Fix include for non x86 architectures").

Cc: Francesco Fusco <fusco@ntop.org>
Cc: Thomas Graf <tgraf@suug.ch>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>