audio_stream: Fix uninitialized data in alignment_constants

Audio stream objects are generally allocated out of zero'd heap
memory, but the computed alignment fields need non-zero values to have
correct behavior.  These were being left as garbage.

Set them to a byte and frame alignmnt of 1, as this corresponds to
pervasive convention in the tree.  But note that a byte alignment of 1
is actually technically incorrect, as all existing DSP targets are on
architectures which don't allow misaligned loads.  But existing
component code is universally coded correctly anyway.

(It's worth pointing out that "set_alignment_constants()" is now
exposed as an API call on abstracted source/sink objects.  But the
only current implementation is on audio_stream.  Future
implementations will need to correctly initialize themselves.)

This is a partial fix for Issue thesofproject#8639

Signed-off-by: Andy Ross <andyross@google.com>

src/audio/audio_stream.c

@@ -141,6 +141,7 @@ void audio_stream_init(struct audio_stream *audio_stream, void *buff_addr, uint3
 	audio_stream->addr = buff_addr;
 	audio_stream->end_addr = (char *)audio_stream->addr + size;
 
+	audio_stream_init_alignment_constants(1, 1, audio_stream);
 	source_init(audio_stream_get_source(audio_stream), &audio_stream_source_ops,
 		    &audio_stream->runtime_stream_params);
 	sink_init(audio_stream_get_sink(audio_stream), &audio_stream_sink_ops,