ethdev: update link status after start

ethdev: update link status after start

Since LSR interrupt is disabled by pmd drivers, link status in rte_eth_device is always down.
Bond slave_configure() enables LSR interrupt on devices to get notification if link status
changes. However, the LSC interrupt at device start time is still lost.

In this fix, call link_update to read link status from hardware
register at device start time.

Signed-off-by: Jia Yu <jyu@vmware.com>
Acked-by: Helin Zhang <helin.zhang@intel.com>