perf map: Use map->dso->kernel + map__kmaps() in map__kmaps()

Its equivalent to using map->groups to obtain the machine struct.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-bdbazuj4ggrmzxdviaqdrdwh@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/map.c

@@ -244,18 +244,11 @@ struct map *map__new2(u64 start, struct dso *dso)
 	return map;
 }
 
-/*
- * Use this and __map__is_kmodule() for map instances that are in
- * machine->kmaps, and thus have map->groups->machine all properly set, to
- * disambiguate between the kernel and modules.
- *
- * When the need arises, introduce map__is_{kernel,kmodule)() that
- * checks (map->groups != NULL && map->groups->machine != NULL &&
- * map->dso->kernel) before calling __map__is_{kernel,kmodule}())
- */
 bool __map__is_kernel(const struct map *map)
 {
-	return machine__kernel_map(map->groups->machine) == map;
+	if (!map->dso->kernel)
+		return false;
+	return machine__kernel_map(map__kmaps((struct map *)map)->machine) == map;
 }
 
 bool __map__is_extra_kernel_map(const struct map *map)