Mapping table from country code to rtw_regulatory, which manages tx power
limit according to countries, is updated. And mapping architecture is also
upgraded. For more precise control on tx power limit, it allows different
rtw_regulatory for different bands logically. Besides, a helper function
to query rtw_regulatory for current band under current country is provided.

For older chips, some newly added rtw_regulatory may not be configured.
To avoid that those chips have no limit on some countries mapping to a
newer rtw_regulatory after table update, a backward selection mechanism
of rtw_regulatory is introduced. It can help chips use a rtw_regulatory
which has been configured as an alternative of a newer one which is not
configured.

In addition, rtw88 actually doesn't manage channel plans by itself.
Instead, it follows them from stack. So, correct some naming about
chplan with regd, and remove the unnecessary channel control for now.
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@codeaurora.org>
Link: https://lore.kernel.org/r/20210830072014.12250-2-pkshih@realtek.com