rt2x00: add driver private field to struct rt2x00_dev

Enhance rt2x00 infrastructure by adding driver specific field to
struct rt2x00_dev.

The new field will be used by rt2800 drivers for chipset registers
access abstraction layer.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Acked-by: Ivo van Doorn <IvDoorn@gmail.com>
Acked-by: Gertjan van Wingerde <gwingerde@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/rt2x00/rt2x00.h b/drivers/net/wireless/rt2x00/rt2x00.h
index 196de8a..c14b0f5 100644
--- a/drivers/net/wireless/rt2x00/rt2x00.h
+++ b/drivers/net/wireless/rt2x00/rt2x00.h
@@ -842,6 +842,11 @@
 	 * Firmware image.
 	 */
 	const struct firmware *fw;
+
+	/*
+	 * Driver specific data.
+	 */
+	void *priv;
 };
 
 /*