rtw89: 8852c: set TX antenna path

To make user space can set TX antenna via iw command. Then, we can diagnose
antenna is connected properly or not, and measure TX power in single path.

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220516005215.5878-3-pkshih@realtek.com