wifi: rtw89: prepare scan leaf functions for wifi 7 ICs

The channel field slightly differs between WiFi 6 and WiFi 7.
So we prepare some required functions in advance, this doesn't change
existing wifi 6 ICs behavior. This H2C prepares the channel list
to be scanned for. With layout as the following:

+--------+--------------------+-------------------+-----------------------+
| header | number of channels | channel info size | channel_info * number |
+--------+--------------------+-------------------+-----------------------+

Signed-off-by: Po-Hao Huang <phhuang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://msgid.link/20240126063356.17857-4-pkshih@realtek.com