1. Remove unused variable of type ol_txrx_stats_req
passed through cdp_txrx_stats api to avoid
compilation break.
2. Add dp_stats file to the Kbuild. This file is
used to collect HTT Statistics for Lithium based
chipsets.
Change-Id: I0252c996d47cc866291d25f35eb9bb9e19073a8b
CRs-Fixed: 2050798