[TG3]: Fix crash during tg3_init_one().

The driver will crash when the chip has been initialized by EFI before
tg3_init_one().  In this case, the driver will call tg3_chip_reset()
before allocating consistent memory.

The bug is fixed by checking for tp->hw_status before accessing it
during tg3_chip_reset().

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