rtw88: 8821c: correct 2.4G tx power for type 2/4 NIC

NIC card saves calibrated TX power index in the efuse(ROM).
Driver loads TX power idex when interface is up.

The problem is type2/4 NICs loads 2.4G TX power index
from wrong position. This patch corrects the offsets.
So, driver loads real 2.4G TX power index for type 2/4 NICs.

2.4G performance increased when using correct TX power index.

Signed-off-by: Guo-Feng Fan <vincent_fann@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210922023637.9357-2-pkshih@realtek.com