perf symbols: No need to check if sym->name is NULL

As it is an array, so will always evaluate to 'true', as reported by
clang:

  builtin-sched.c:2070:19: error: address of array 'sym->name' will always evaluate to 'true' [-Werror,-Wpointer-bool-conversion]
                  if (sym && sym->name) {
                          ~~ ~~~~~^~~~
  1 warning generated.

So just ditch all those useless checks.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-ydpm927col06paixb775jjx5@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index daceb32..270eb2d 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -2067,7 +2067,7 @@ static void save_task_callchain(struct perf_sched *sched,
 			break;
 
 		sym = node->sym;
-		if (sym && sym->name) {
+		if (sym) {
 			if (!strcmp(sym->name, "schedule") ||
 			    !strcmp(sym->name, "__schedule") ||
 			    !strcmp(sym->name, "preempt_schedule"))