ASoC: tlv320dac33: Limit the US_TO_SAMPLES macro

Limit the time window to maximum 1s in the macro.
The driver deals with much shorter times (<200ms).
This will fix a rare division by zero bug in Mode1.
This could happen, when the work is not executed in
time (within mode1_latency) after the interrupt.
In this case the DAC33 will not receive the needed
nSample command in time, and enters to an unknown
state, and won't recover.
In such event the time window will increase, and
eventually going to be bigger than 1s, resulting
devision by zero.
Signed-off-by: NPeter Ujfalusi <peter.ujfalusi@nokia.com>
Acked-by: NMark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: NLiam Girdwood <lrg@slimlogic.co.uk>

sound/soc/codecs/tlv320dac33.c

@@ -58,7 +58,7 @@
 	(1000000000 / ((rate * 1000) / samples))
 
 #define US_TO_SAMPLES(rate, us) \
-	(rate / (1000000 / us))
+	(rate / (1000000 / (us < 1000000 ? us : 1000000)))
 
 #define UTHR_FROM_PERIOD_SIZE(samples, playrate, burstrate) \
 	((samples * 5000) / ((burstrate * 5000) / (burstrate - playrate)))