wifi: rtw89: initialize multi-channel handling

We prepare to deal with multiple channels via new entity modes.
* MCC_PREPARE:	Transitional mode before MCC
* MCC:		Multi-Channel Concurrent mode
And, enum of sub-entity is extended for second channel context.

We add the entry flow of multi-channel handling and the core stuffs
for extended index of sub-entity. And, we now deal with the filling
of entity channels' info in entity recalc where we know the number
of active chanctx. However, the other detail coding of MCC start/stop
will be implemented in the following.

Besides, chanctx listener struct is pre-added in chip info. Each
component can add callback type in chanctx listener and configure
its callback function to react according to chanctx states. We know
at least RFK (RF calibration) and BTC (BT coexistence) will require
such callbacks.

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/20230816082133.57474-7-pkshih@realtek.com