wifi: rtw88: Add rtw8821a_table.{c,h}

These contain various arrays for initialising RTL8821AU. Also TX power
limits.

Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/087c7260-fcc3-4e22-886b-ac477cad9198@gmail.com