rsi: rsi_91x_usb_ops: Source file headers are not good candidates for kernel-doc

Fixes the following W=1 kernel build warning(s):

 drivers/net/wireless/rsi/rsi_91x_usb_ops.c:22: warning: Incorrect use of kernel-doc format:  * rsi_usb_rx_thread() - This is a kernel thread to receive the packets from
 drivers/net/wireless/rsi/rsi_91x_usb_ops.c:29: warning: Function parameter or member 'common' not described in 'rsi_usb_rx_thread'

Cc: Amitkumar Karwar <amitkarwar@gmail.com>
Cc: Siva Rebbagondla <siva8118@gmail.com>
Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20201102112410.1049272-5-lee.jones@linaro.org

drivers/net/wireless/rsi/rsi_91x_usb_ops.c

-/**
+/*
  * Copyright (c) 2014 Redpine Signals Inc.
  *
  * Permission to use, copy, modify, and/or distribute this software for any