schedule: zephyr_domain: change overrun semantics for LL stats

Change the logic how overrun count is reported out in the
low-latency scheduler statistics reporting. Instead of resetting
the overrun count after every window, keep a cumulative count
of overruns seen. Overruns are in practise a rare occurrence and
this change makes the CONFIG_SCHEDULE_LL_STATS_LOG_EVERY_OTHER_WINDOW
option more useful as one can still track overruns for all
executed iterations, even if reporting is done at a slower pace.

Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>

Author: kv2019i

src/schedule/zephyr_domain.c

@@ -131,7 +131,6 @@ static void zephyr_domain_thread_fn(void *p1, void *p2, void *p3)
 			stats_report(runs, core, cycles_sum, cycles_max, overruns);
 			cycles_sum = 0;
 			cycles_max = 0;
-			overruns = 0;
 		}
 #endif /* CONFIG_SCHEDULE_LL_STATS_LOG */