wifi: rtw89: concentrate parameter control for setting channel callback

For future support on multiple channels by multiple sub-entities,
we need to manage parameters of each channel instance like rtw89_chan,
rtw89_mac_idx, rtw89_phy_idx. So, we adjust related channel callback
functions and centrally conrtol these parameters in set_channel().

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/20220809104952.61355-8-pkshih@realtek.com