staging: rtl8192u: Remove unnecessary comment

The <linux/config.h> header file is not used anymore,
so it is commented out in this file.This patch deletes
that unnecessary comment.

Signed-off-by: Navya Sri Nizamkari <navyasri.tech@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>