igb: release software locked semaphores on initialization

igb: release software locked semaphores on initialization

It may happen that DPDK application gets killed while having
acquired locks on the ethernet hardware, causing these locks to
be never released. On next restart of the application, DPDK
skip those ports because it can not acquire the lock,
this may cause some ports (or even complete board if SMBI is locked)
to be inaccessible from DPDK application until reboot of the
hardware.

This patch release locks that are supposed to be locked due to
an improper exit of the application.

Signed-off-by: Didier Pallard <didier.pallard@6wind.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>