selftests/bpf: less spam in the log for message matching

When running test_loader based tests in the verbose mode each matched
message leaves a trace in the stderr, e.g.:

./test_progs -vvv -t ...
validate_msgs:PASS:expect_msg 0 nsec
validate_msgs:PASS:expect_msg 0 nsec
validate_msgs:PASS:expect_msg 0 nsec
validate_msgs:PASS:expect_msg 0 nsec
validate_msgs:PASS:expect_msg 0 nsec

This is not very helpful when debugging such tests and clobbers the
log a lot.

Signed-off-by: Eduard Zingerman <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Alexei Starovoitov <[e-mail]>

tools/testing/selftests/bpf/test_loader.c

···
 			}
 		}
 
-		if (!ASSERT_OK_PTR(match, "expect_msg")) {
+		if (!match) {
+			PRINT_FAIL("expect_msg\n");
 			if (env.verbosity == VERBOSE_NONE)
 				emit_fn(log_buf, true /*force*/);
 			for (j = 0; j <= i; j++) {