bnx2x: Removing the PMF indication when unloading

When the PMF flag is set, the driver can access the HW freely. When the
driver is unloaded, it should not access the HW. The problem caused fatal
errors when "ethtool -i" was called after the calling instance was unloaded
and another instance was already loaded

Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>