perf top: Don't complain about lack of vmlinux when not resolving some kernel samples

Recently we got a case where a kernel sample wasn't being resolved due
to a bug that was not setting the end address on kernel functions
implemented in assembly (see Link: tag), and then those were not being
found by machine__resolve() -> map__find_symbol().

So we ended up with:

  # perf top --stdio
  PerfTop: 0 irqs/s  kernel: 0%  exact: 0% lost: 0/0 drop: 0/0 [cycles/P]
  -----------------------------------------------------------------------

  Warning:
  A vmlinux file was not found.
  Kernel samples will not be resolved.
  ^Z
  [1]+  Stopped                 perf top --stdio
  #

But then resolving all other kernel symbols.

So just fixup the logic to only print that warning when there are no
symbols in the kernel map.

Fixes: d88205d ("perf dso: Add dso__has_symbols() method")
Reviewed-by: Namhyung Kim <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Ian Rogers <[email protected]>
Cc: Christophe Leroy <[email protected]>
Cc: James Clark <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Kan Liang <[email protected]>
Link: https://lore.kernel.org/lkml/Z3buKhcCsZi3_aGb@x1
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

Author: acmel

tools/perf/builtin-top.c

@@ -809,7 +809,7 @@ static void perf_event__process_sample(const struct perf_tool *tool,
 		 * invalid --vmlinux ;-)
 		 */
 		if (!machine->kptr_restrict_warned && !top->vmlinux_warned &&
-		    __map__is_kernel(al.map) && map__has_symbols(al.map)) {
+		    __map__is_kernel(al.map) && !map__has_symbols(al.map)) {
 			if (symbol_conf.vmlinux_name) {
 				char serr[256];