bpf, test_verifier: fix a test case error result on unprivileged

Running ./test_verifier as unprivileged lets 1 out of 98 tests fail:

  [...]
  #71 unpriv: check that printk is disallowed FAIL
  Unexpected error message!
  0: (7a) *(u64 *)(r10 -8) = 0
  1: (bf) r1 = r10
  2: (07) r1 += -8
  3: (b7) r2 = 8
  4: (bf) r3 = r1
  5: (85) call bpf_trace_printk#6
  unknown func bpf_trace_printk#6
  [...]

The test case is correct, just that the error outcome changed with
ebb676da ("bpf: Print function name in addition to function id").
Same as with e00c7b21 ("bpf: fix multiple issues in selftest suite
and samples") issue 2), so just fix up the function name.

Fixes: ebb676da ("bpf: Print function name in addition to function id")
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

tools/testing/selftests/bpf/test_verifier.c

@@ -1059,7 +1059,7 @@ static struct bpf_test tests[] = {
 			BPF_MOV64_IMM(BPF_REG_0, 0),
 			BPF_EXIT_INSN(),
 		},
-		.errstr_unpriv = "unknown func 6",
+		.errstr_unpriv = "unknown func bpf_trace_printk#6",
 		.result_unpriv = REJECT,
 		.result = ACCEPT,
 	},