ath10k: enable firmware peer stats info for wmi tlv

For wmi tlv type, firmware disable peer stats info by default, after
enable it, firmware will report WMI_TLV_PEER_STATS_INFO_EVENTID if
ath10k send WMI_TLV_REQUEST_PEER_STATS_INFO_CMDID to firmware.

Enable it will only set a flag in firmware, firmware will not report
it without receive request WMI command.

Tested with QCA6174 SDIO with firmware WLAN.RMH.4.4.1-00042.

Signed-off-by: Wen Gong <wgong@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200427080416.8265-2-wgong@codeaurora.org