selftests/bpf: verifier/helper_access_var_len.c converted to inline assembly

Test verifier/helper_access_var_len.c automatically converted to use inline assembly.

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20230325025524.144043-21-eddyz87@gmail.com


Signed-off-by: Alexei Starovoitov <ast@kernel.org>