CHROMIUM: wireless: Add stats for tx latency

Change transmit latency histogram to linear scale from exponential scale
to get better resolution.

commit a100152b031b ("CHROMIUM: wireless-4.2: Add stats for tx latency")
https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/541625



BUG=b:122726016
TEST=cat /sys/kernel/debug/ieee80211/phyX/ath10k/tx_delay_histogram

Cq-Depend: chromium:1677132
Change-Id: I7697d01107a19113b119894408a58f131a05c54f
Signed-off-by: Ratheesh S P <ratheeshs@google.com>
Reviewed-on: https://chromium-review.googlesource.com/1676933


Tested-by: Ratheesh Selvakumar Pappa <ratheeshs@google.com>
Commit-Ready: Ratheesh Selvakumar Pappa <ratheeshs@google.com>
Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>
Reviewed-by: Danny Mitzel <mitzel@google.com>
Reviewed-by: Kan Yan <kyan@chromium.org>