bnx2: Fix shutdown sequence

The pci shutdown handler added in:

    bnx2: Add pci shutdown handler
    commit 25bfb1dd



created a shutdown down sequence without chip reset if the device was
never brought up.  This can cause the firmware to shutdown the PHY
prematurely and cause MMIO read cycles to be unresponsive.  On some
systems, it may generate NMI in the bnx2's pci shutdown handler.

The fix is to tell the firmware not to shutdown the PHY if there was
no prior chip reset.

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