U-NII-4 band, i.e 5.9GHz channels, can be supported by chip 8852C, 8852B
and 8851B. But, it is not supported by chip 8852A. Flag support_unii4 is
added in chip info and defined by chip accordingly to indicate that.
We reference this flag of runtime chip to decide whether to register
5.9GHz channels.

After that, we consider if U-NII-4 band is allowed by our regulatory
rule of U-NII-4. If chip::support_unii4 but not regd::allow_unii4,
we stll do not register 5.9GHz channels.
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/20230508081211.38760-4-pkshih@realtek.com