signal: Replace memset(info,...) with clear_siginfo for clarity

The function clear_siginfo is just a nice wrapper around memset so
this results in no functional change.  This change makes mistakes
a little more difficult and it makes it clearer what is going on.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

kernel/time/posix-timers.c

@@ -462,7 +462,7 @@ static struct k_itimer * alloc_posix_timer(void)
 		kmem_cache_free(posix_timers_cache, tmr);
 		return NULL;
 	}
-	memset(&tmr->sigq->info, 0, sizeof(siginfo_t));
+	clear_siginfo(&tmr->sigq->info);
 	return tmr;
 }