net/igb: support setting link up or down
net/igb: support setting link up or down

Add driver functions to set link state up or down.

Signed-off-by: Aaron Campbell <5a7a6a189b47cd31d24667a751e4003cd04eced5@arbor.net>
Acked-by: Wenzhuo Lu <58cb9036bdff9a5412edc3b9f70e105ccf59954f@intel.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk