Currently the RX rates stats is obtained from data frames from
driver. There is no data frames for driver to get rates stats
for a few seconds after ASSOC/REASSOC/ROAMING, so driver has to
gets rates stats by parsing the rateflags and the raw_rate from
FW until a data frame is received. However, the raw_rate from FW
is sometimes inaccurate after ASSOC/REASSOC/ROAMING. This is hard
to be seen since the period between ASSOC/REASSOC/ROAMING and
receiving a data frame is not long. To address this issue, using
TX rate stats to figure out max rate before receiving a data frame.
Change-Id: I83613447f56fc892ec6d20527ea1a872778afae1
CRs-Fixed: 3449455
ba56ebcd15