wifi: rtw89: use struct and le32_get_bits to access RX info

If received packet type is PPDU status, RX info provides information
attached by MAC hardware, and mention how long BB information attached.

This conversion patch doesn't change logic at all.

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230522122513.13559-3-pkshih@realtek.com