wifi: rtw88: usb: Enable switching the RTL8814AU to USB 3

The Realtek wifi 5 devices which support USB 3 are weird: when first
plugged in, they pretend to be USB 2. The driver needs to send some
commands to the device, which make it disappear and come back as a
USB 3 device.

The method used to switch the RTL8812AU also works for the RTL8814AU.

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://patch.msgid.link/d3608f70-e04f-4f6b-987a-022c8e317165@gmail.com