ixgbe: convert to ethtool set_phys_id

Based on the original patch submitted by Stephen Hemminger.

This patch makes the following changes:
- Change ETHTOOL_ID_INACTIVE return value to 2 (blinks/sec)
- Fix restoring of IXGBE_LEDCTL

CC: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Tested-by: Evan Swanson <evan.swanson@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>