rtw88: fix wrong rx power calculation

Fix the wrong RF path for CCK rx power calculation.

Fixes: e3037485

 ("rtw88: new Realtek 802.11ac driver")
Signed-off-by: Tsang-Shian Lin <thlin@realtek.com>
Signed-off-by: Yan-Hsuan Chuang <yhchuang@realtek.com>
Reviewed-by: Chris Chiu <chiu@endlessm.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>