Fix audio record pre-processing

proc_buf_out consistently initialized.
intermediate scratch buffers consistently initialized.
prevent read failure from overwriting memory.

Test: POC, CTS, camera record
Bug: 62873231
Change-Id: Ie26e12a419a5819c1c5c3a0bcf1876d6d7aca686
(cherry picked from commit 6d7b330c27efba944817e647955da48e54fd74eb)

static int in_set_sample_rate(struct audio_stream *stream, uint32_t rate)
{
 (void)stream;
 (void)rate;
 return -ENOSYS;
}

static int in_set_sample_rate(struct audio_stream *stream, uint32_t rate)
{
 (void)stream;
 (void)rate;
 return -ENOSYS;
}
