pps: use BUG_ON for kernel API safety checks

This way less overhead is involved when running production kernel.  If you
want to debug a pps client module please define DEBUG to enable the
checks.
Signed-off-by: Alexander Gordeev <lasaine@lvk.cs.msu.su>
Acked-by: Rodolfo Giometti <giometti@linux.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/pps/kapi.c

@@ -166,10 +166,8 @@ void pps_event(struct pps_device *pps, struct pps_event_time *ts, int event,
 	int captured = 0;
 	struct pps_ktime ts_real;
 
-	if ((event & (PPS_CAPTUREASSERT | PPS_CAPTURECLEAR)) == 0) {
-		dev_err(pps->dev, "unknown event (%x)\n", event);
-		return;
-	}
+	/* check event type */
+	BUG_ON((event & (PPS_CAPTUREASSERT | PPS_CAPTURECLEAR)) == 0);
 
 	dev_dbg(pps->dev, "PPS event at %ld.%09ld\n",
 			ts->ts_real.tv_sec, ts->ts_real.tv_nsec);