qcacmn: fix incorrect ext_stats calculation

Currently when query REO stats, each time REO will response
cumulative REO stats per TID, while host side count them as
delta stats between each query.
Reset host stats to 0 before each query, and if query timeout
happened, use the last saved stats for this time query.

Change-Id: I29e986b3c8859f5c3d1b557d9cc980a52219d664
CRs-Fixed: 2743352