Staging: hv: vmbus: Get rid of the ext field in struct hv_device

Now that we have eliminated all uses of the ext field in struct hv_device,
get rid of the ext field.
Signed-off-by: NK. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: NHaiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/staging/hv/hyperv.h

@@ -827,9 +827,6 @@ struct hv_device {
 	struct device device;
 
 	struct vmbus_channel *channel;
-
-	/* Device extension; */
-	void *ext;
 };