bpf: Revert bpf_overrid_function() helper changes.

NACK'd by x86 maintainer.

Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/bpf/bpf_helpers.h

@@ -82,8 +82,7 @@ static int (*bpf_perf_event_read_value)(void *map, unsigned long long flags,
 static int (*bpf_perf_prog_read_value)(void *ctx, void *buf,
 				       unsigned int buf_size) =
 	(void *) BPF_FUNC_perf_prog_read_value;
-static int (*bpf_override_return)(void *ctx, unsigned long rc) =
-	(void *) BPF_FUNC_override_return;
+
 
 /* llvm builtin functions that eBPF C program may use to
  * emit BPF_LD_ABS and BPF_LD_IND instructions