wifi: rtw89: regd: support loading regd table from fw element

Regd table is a table that we use to describe how to map Realtek RF TX
power settings on different countries. Originally, a common regd table
for all chips is implemented in driver. However, in order to work on all
chips, the common regd table might have some trade-off. So now, there are
also an individual regd table for some chips. And, we support loading it
from FW element.

Signed-off-by: Zong-Zhe Yang <kevin_yang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/20250120032723.19042-2-pkshih@realtek.com