ASoC: intel: atom: Fix breakage for PCM buffer address setup

The commit 2e6b8363 ("ASoC: intel: atom: Fix reference to PCM
buffer address") changed the reference of PCM buffer address to
substream->runtime->dma_addr as the buffer address may change
dynamically.  However, I forgot that the dma_addr field is still not
set up for the CONTINUOUS buffer type (that this driver uses) yet in
5.14 and earlier kernels, and it resulted in garbage I/O.  The problem
will be fixed in 5.15, but we need to address it quickly for now.

The fix is to deduce the address again from the DMA pointer with
virt_to_phys(), but from the right one, substream->runtime->dma_area.

Fixes: 2e6b8363 ("ASoC: intel: atom: Fix reference to PCM buffer address")
Reported-and-tested-by: Hans de Goede <hdegoede@redhat.com>
Cc: <stable@vger.kernel.org>
Acked-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/2048c6aa-2187-46bd-6772-36a4fb3c5aeb@redhat.com
Link: https://lore.kernel.org/r/20210819152945.8510-1-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/soc/intel/atom/sst-mfld-platform-pcm.c

@@ -127,7 +127,7 @@ static void sst_fill_alloc_params(struct snd_pcm_substream *substream,
 	snd_pcm_uframes_t period_size;
 	ssize_t periodbytes;
 	ssize_t buffer_bytes = snd_pcm_lib_buffer_bytes(substream);
-	u32 buffer_addr = substream->runtime->dma_addr;
+	u32 buffer_addr = virt_to_phys(substream->runtime->dma_area);
 
 	channels = substream->runtime->channels;
 	period_size = substream->runtime->period_size;