bnx2x: Change to D3hot only on removal

This changes the PCI power management scheme of the bnx2x driver to be similar
to those of most network drivers - the driver will now changes the power state
into D3hot whenever the driver will be removed, instead of whenever an
interface is unloaded.

This change enables the driver to access its eeprom via ethtool callbacks
even when interfaces are unloaded (such access requires the function to be
in D0active).

Signed-off-by: Yuval Mintz <yuvalmin@broadcom.com>
Signed-off-by: Ariel Elior <ariele@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>