ASoC: AMD: Always subtract bytescount

It is always correct to subtract out the starting bytescount value.  Even
in the case of 2^64 byte rollover (292 Million Years in the future
@ 48000 Hz) the math still works out.
Signed-off-by: NDaniel Kurtz <djkurtz@chromium.org>
Signed-off-by: NMark Brown <broonie@kernel.org>

sound/soc/amd/acp-pcm-dma.c

@@ -995,8 +995,7 @@ static snd_pcm_uframes_t acp_dma_pointer(struct snd_pcm_substream *substream)
 	buffersize = frames_to_bytes(runtime, runtime->buffer_size);
 	bytescount = acp_get_byte_count(rtd);
 
-	if (bytescount > rtd->bytescount)
-		bytescount -= rtd->bytescount;
+	bytescount -= rtd->bytescount;
 	pos = do_div(bytescount, buffersize);
 	return bytes_to_frames(runtime, pos);
 }