wifi: rtw89: declare support for mac80211 chanctx ops by chip

Some HW features are required if we hook chanctx ops to mac80211. With it,
mac80211 would expect the HW-supported variant ops exists on some behavior,
e.g. HW scan. But, HW features may depend on chip's FW or its development.
Besides, how many chanctx can be supported also depends on chip design.
We can neither decide whether to generally support chanctx ops nor how many
chanctx can be supported.

So, support_chanctx_num is added under chip info to deal with this by chip.
For now, all chip configure support_chanctx_num as 0. We haven't really
hook chanctx ops yet. So, chip can run without mac80211 chanctx as before.

Signed-off-by: Zong-Zhe Yang <kevin_yang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220809104952.61355-13-pkshih@realtek.com