Audio: aec: optimize acoustic echo cancellation processing

This check-in proposal enhances the audio Echo Cancellation
AEC) implementation. The enhancements seek to enhance loop
designs and memory copy operations, reducing cycle
consumption.

When pointer arithmetic is substituted for array
indexing, it expedites performance and enhances
data processing. To maximize efficiency, data copy
verification is done outside of the loop, and
performance is increased by using pointer arithmetic
instead of inner loops.

Error management is included when the size of the
destination buffer is exceeded by the source data.
Before converting or copying data, the pointers
"ref," "src," and "dst" are verified to be inside
the valid range of "ref_buf," "src_buf," and
"dst_buf."

These changes improve the code's robustness and
efficiency by adding the necessary error checks.

Signed-off-by: shastry <[email protected]>