wifi: rtw89: parse phycap of TX/RX antenna number

Two fields, TX/RX ANT NUM, are introduced to address variant TX/RX antenna
number of hardware. For example, a 1x1 chip with TX diversity, TX NSS = 1
and TX/RX ANT NUM = 2.

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220908074140.39776-3-pkshih@realtek.com