sched_football: use get_numcpus()

sched_football can hang in systems where not all CPU cores
are available, using get_numcpus() to account
for things like isolated cores.

Link: https://lore.kernel.org/ltp/20250117135745.909549-3-afazekas@redhat.com/
Reviewed-by: Cyril Hrubis <chrubis@suse.cz>
Reviewed-by: Petr Vorel <pvorel@suse.cz>
Signed-off-by: Attila Fazekas <afazekas@redhat.com>

Author: afazekas

testcases/realtime/func/sched_football/sched_football.c

@@ -140,7 +140,7 @@ static void do_test(void)
 	int i;
 
 	if (players_per_team == 0)
-		players_per_team = sysconf(_SC_NPROCESSORS_ONLN);
+		players_per_team = get_numcpus();
 
 	tst_atomic_store(0, &players_ready);