XHCI: Add missing set-address delay.

The USB < 3.0 init code has this, and the XHCI spec indicates that
software is responsible for dealing with this still, indeed.

Noticed by rudolfc when testing some USB audio devices in #1045.

src/add-ons/kernel/busses/usb/xhci.cpp

@@ -1532,6 +1532,9 @@ XHCI::AllocateDevice(Hub *parent, int8 hubAddress, uint8 hubPort,
 		ENDPOINT_0_STATE_GET(_ReadContext(
 			&device->device_ctx->endpoints[0].dwendpoint0)));
 
+	// Wait a bit for the device to complete addressing
+	snooze(USB_DELAY_SET_ADDRESS);
+
 	// Create a temporary pipe with the new address
 	ControlPipe pipe(parent);
 	pipe.SetControllerCookie(endpoint0);