tg3: remove redundant pm init code

Pci_enable_device() will set device pm state to D0, so
it's no need to do it again in tg3_init_one().

Acked-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>