wifi: rtw89: use struct and le32_get_bits() to access received PHY status IEs

PHY status IEs generated by BB hardware is to provide more detail
information related to received packets, such as RSSI and bandwidth.

To avoid type casting, change buf type from u8* to void* as well.

This 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/20230522122513.13559-4-pkshih@realtek.com