asoc: Fix bytes_read in compress record usecase with timestamp

In compress_capture usecase with timestamp enabled, distortion
is observed when we record for long time. This is because of
incorrect calculation of buffer_sent. To fix add timestamp header
offset along with buffer length to bytes_read.

Change-Id: I82fcab1d242380a5b2732953feb91b9353b26b12
Signed-off-by: Sachin Mohan Gadag <sgadag@codeaurora.org>