tg3: Call tg3_netif_stop() from tg3_stop()

instead of making separate tg3_napi_disable() and netif_tx_disable() calls.

Update version to 3.126.

Signed-off-by: Nithin Nayak Sujir <nsujir@broadcom.com>
Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>