Revert "mwifiex: handle race during mwifiex_usb_disconnect"

This reverts commit b817047ae70c0bd67b677b65d0d69d72cd6e9728.

We have a better fix for this issue, which will be sent on top
of this revert.

Signed-off-by: Ganapathi Bhat <gbhat@marvell.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/marvell/mwifiex/usb.c

@@ -644,9 +644,6 @@ static void mwifiex_usb_disconnect(struct usb_interface *intf)
 					 MWIFIEX_FUNC_SHUTDOWN);
 	}
 
-	if (adapter->workqueue)
-		flush_workqueue(adapter->workqueue);
-
 	mwifiex_usb_free(card);
 
 	mwifiex_dbg(adapter, FATAL,