ethdev: allow close function to return an error

ethdev: allow close function to return an error

The API function rte_eth_dev_close() was returning void.
The return type is changed to int for notifying of errors.

If an error happens during a close operation,
the status of the port is undefined,
a maximum of resources having been freed.

Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
Reviewed-by: Liron Himi <lironh@marvell.com>
Acked-by: Stephen Hemminger <stephen@networkplumber.org>
Acked-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
Reviewed-by: Ferruh Yigit <ferruh.yigit@intel.com>