Use osmo_libusb_{init,exit}() instead of libusb_{init,exit}()

We use other osmo_libusb_* functions later in the code, so it is best
to initialize the library via libosmousb, and not directly.

Change-Id: I2fd981935e1420e529f5dd8a98edd347c317284c

host/src/simtrace2-cardem-pcsc.c

@@ -633,7 +633,7 @@ close_exit:
 	if (transp->usb_devh)
 		libusb_close(transp->usb_devh);
 
-	libusb_exit(NULL);
+	osmo_libusb_exit(NULL);
 do_exit:
 	return ret;
 }