8822c used to count OFDM FA count by subtracting tx count from FA count.
But it need to substract more counters to be accurate.

However, we can count it by adding up all of the FA counters we want.
And it is simpler to add than list all of the components to substract.
Signed-off-by: Yan-Hsuan Chuang <yhchuang@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>