wifi: rtw89: refactor flow that hw scan handles channel list

FW has a limited amount of channels that can be dealt with by one HW scan
H2C command. Based on the limit, channels in scan request might be parsed
into SW structure piece by piece along with multiple HW scan H2C commands.
But, in order to estimate things of entire HW scan process, it's required
to have the whole parsed channel list when HW scan is going to start. So,
tweak HW scan flow to prepare the whole channel list ahead. Still, each HW
scan H2C command takes allowed amount of channels from the list according
to the limit.

Signed-off-by: Zong-Zhe Yang <kevin_yang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/20250422014620.18421-5-pkshih@realtek.com