Revert "ath9k_hw: implement temperature compensation support for AR9003+"

This reverts commit 171f6402 ("ath9k_hw: implement temperature compensation
support for AR9003+"). Some users report that this commit causes a regression
in performance under some conditions.

Fixes: 171f6402 ("ath9k_hw: implement temperature compensation support for AR9003+")
Cc: <stable@vger.kernel.org> # 4.8
Signed-off-by: Felix Fietkau <nbd@nbd.name>
[kvalo@qca.qualcomm.com: improve commit log]
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>