wifi: rtlwifi: Adjust rtl8192d-common for USB

A few of the shared functions need small changes for the USB driver:
 - firmware loading
 - efuse reading
 - rate mask updating
 - rf register reading
 - initial gain for scanning

Also, add a few macros to wifi.h and initialise rtlhal.interfaceindex
for USB devices.

Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://msgid.link/28100330-f421-4b85-b41b-f1045380cef2@gmail.com