net: lan78xx: fix rx handling before first packet is send

As long the bh tasklet isn't scheduled once, no packet from the rx path
will be handled. Since the tx path also schedule the same tasklet
this situation only persits until the first packet transmission.
So fix this issue by scheduling the tasklet after link reset.

Link: https://github.com/raspberrypi/linux/issues/2617
Fixes: 55d7de9d ("Microchip's LAN7800 family USB 2/3 to 10/100/1000 Ethernet")
Suggested-by: NFloris Bos <bos@je-eigen-domein.nl>
Signed-off-by: NStefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/usb/lan78xx.c

@@ -1242,6 +1242,8 @@ static int lan78xx_link_reset(struct lan78xx_net *dev)
 			mod_timer(&dev->stat_monitor,
 				  jiffies + STAT_UPDATE_TIMER);
 		}
+
+		tasklet_schedule(&dev->bh);
 	}
 
 	return ret;