net/ixgbe: ensure link status is updated

net/ixgbe: ensure link status is updated

In case of fiber and link speed set to 1Gb at peer side (with autoneg
or with defined speed), link status could be not properly updated at
time cable is plugged-in.
Indeed if cable was not plugged when device has been configured and
started then link status will not be updated properly with new speed
as no link setup will be triggered.

To avoid this issue, IXGBE_FLAG_NEED_LINK_CONFIG is set to try a link
setup each time link_update() is triggered and current link status is
down. When cable is plugged-in, link setup will be performed via
ixgbe_setup_link().

Signed-off-by: Laurent Hardy <laurent.hardy@6wind.com>
Acked-by: Wei Dai <wei.dai@intel.com>