wifi: rtl8xxxu: Add LED control code for RTL8192CU family

wifi: rtl8xxxu: Add LED control code for RTL8192CU family

Also, don't set bit 7 of LEDCFG2 for RTL8192CU. If bit 7 is set the LED
never turns on. In this family only RTL8188CUS needs bit 7 of LEDCFG2
set.

Software control (on/off) and hardware control (automatic blinking)
tested with Netcore NW362 (RTL8192CU).

Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Reviewed-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://msgid.link/4b5970cf-d28b-415a-b911-82cdb5e9ce99@gmail.com