wifi: rtw89: add chip_ops::query_rxdesc() and rxd_len as helpers to support newer chips

The next generation chips use different RX descriptor format, so add
a chip_ops to hook suitable handlers. Also, the length of RX descriptor is
different, so add a variable to store the length according to chip and
descriptor content dynamically. Then, the code can be more general.

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230522122513.13559-2-pkshih@realtek.com