usbnet: Fix up 'FLAG_POINTTOPOINT' and 'FLAG_MULTI_PACKET' overlaps.

USB tethering does not work anymore since 2.6.39-rc2, but it's okay in
-rc1. The root cause is the new added mask code 'FLAG_POINTTOPOINT'
overlaps 'FLAG_MULTI_PACKET' in include/linux/usb/usbnet.h, this
causes logic issue in rx_process(). This patch cleans up the overlap.

Reported-and-Tested-by: Gottfried Haider <[e-mail]>
Signed-off-by: Huajun Li <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/linux/usb/usbnet.h

···
  * Indicates to usbnet, that USB driver accumulates multiple IP packets.
  * Affects statistic (counters) and short packet handling.
  */
-#define FLAG_MULTI_PACKET	0x1000
-#define FLAG_RX_ASSEMBLE	0x2000	/* rx packets may span >1 frames */
+#define FLAG_MULTI_PACKET	0x2000
+#define FLAG_RX_ASSEMBLE	0x4000	/* rx packets may span >1 frames */
 
 	/* init device ... can sleep, or cause probe() failure */
 	int	(*bind)(struct usbnet *, struct usb_interface *);