rtlwifi: rtl_usb: Fix missing entry in USB driver's private data

BugLink: http://bugs.launchpad.net/bugs/1666421

These drivers need to be able to reference "struct ieee80211_hw" from
the driver's private data, and vice versa. The USB driver failed to
store the address of ieee80211_hw in the private data. Although this
bug has been present for a long time, it was not exposed until
commit ba9f93f8 ("rtlwifi: Fix enter/exit power_save").

Fixes: ba9f93f8 ("rtlwifi: Fix enter/exit power_save")
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
(cherry picked from commit 60f59ce0)
Signed-off-by: Joseph Salisbury <joseph.salisbury@canonical.com>
Acked-by: Brad Figg <brad.figg@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Brad Figg <brad.figg@canonical.com>

drivers/net/wireless/realtek/rtlwifi/usb.c

@@ -1073,6 +1073,7 @@ int rtl_usb_probe(struct usb_interface *intf,
 		return -ENOMEM;
 	}
 	rtlpriv = hw->priv;
+	rtlpriv->hw = hw;
 	rtlpriv->usb_data = kzalloc(RTL_USB_MAX_RX_COUNT * sizeof(u32),
 				    GFP_KERNEL);
 	if (!rtlpriv->usb_data)