cangen: don't compare floating-point gap with ‘==’

Fixes the following warning:

| cangen.c:524:7: warning: comparing floating-point with ‘==’ or ‘!=’ is unsafe [-Wfloat-equal]
|   524 |   if (gap && burst_sent_count >= burst_count) /* gap == 0 => performance test :-] */
|       |       ^~~

Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

cangen.c

@@ -521,7 +521,8 @@ resend:
 		}
 
 		burst_sent_count++;
-		if (gap && burst_sent_count >= burst_count) /* gap == 0 => performance test :-] */
+		if ((ts.tv_sec || ts.tv_nsec) &&
+		    burst_sent_count >= burst_count)
 			if (nanosleep(&ts, NULL))
 				return 1;