eal: remove FINISHED lcore state

eal: remove FINISHED lcore state

FINISHED state seems to be used to indicate that the worker's update
of the 'state' is not visible to other threads. There seems to be no
requirement to have such a state.

Since the FINISHED state is removed, the API rte_eal_wait_lcore
is updated to always return the status of the last function that
ran in the worker core.

Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Ola Liljedahl <ola.liljedahl@arm.com>
Reviewed-by: Feifei Wang <feifei.wang2@arm.com>