ASoC: omap-mcbsp: Fix latency value calculation for pm_qos

The latency number is in usec for the pm_qos. Correct the calculation to
give us the time in usec

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Acked-by: Jarkko Nikula <jarkko.nikula@bitmer.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/omap/omap-mcbsp.c

@@ -308,9 +308,9 @@ static int omap_mcbsp_dai_hw_params(struct snd_pcm_substream *substream,
 			pkt_size = channels;
 		}
 
-		latency = ((((buffer_size - pkt_size) / channels) * 1000)
-				 / (params->rate_num / params->rate_den));
-
+		latency = (buffer_size - pkt_size) / channels;
+		latency = latency * USEC_PER_SEC /
+			  (params->rate_num / params->rate_den);
 		mcbsp->latency[substream->stream] = latency;
 
 		omap_mcbsp_set_threshold(substream, pkt_size);