eal: fix memory ordering around lcore task accesses

eal: fix memory ordering around lcore task accesses

Ensure that the memory operations before the call to
rte_eal_remote_launch are visible to the worker thread.
Use the function pointer to execute in worker thread
as the guard variable.

Ensure that the memory operations in worker thread, that happen
before it returns the status of the assigned function, are
visible to the main thread. Use the variable containing the
lcore's state as the guard variable.

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>