staging: rtl8192u: fix control-message timeouts

USB control-message timeouts are specified in milliseconds and should
specifically not vary with CONFIG_HZ.

Fixes: 8fc8598e

 ("Staging: Added Realtek rtl8192u driver to staging")
Cc: stable@vger.kernel.org      # 2.6.33
Acked-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20211025120910.6339-2-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>