rtl8187: fix control-message timeouts

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

Fixes: 605bebe2

 ("[PATCH] Add rtl8187 wireless driver")
Cc: stable@vger.kernel.org      # 2.6.23
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20211025120522.6045-4-johan@kernel.org