bnx2: Check netif_running() in all ethtool operations.

We need to check netif_running() state in most ethtool operations
and properly handle the !netif_running() state where the chip is
in an uninitailzed state or low power state that may not accept
any MMIO.

Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: Benjamin Li <benli@broadcom.com>
Signed-off-by: Matt Carlson <mcarlson@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>