ethdev: change allmulticast mode API to return errors

ethdev: change allmulticast mode API to return errors

Change rte_eth_allmulticast_enable()/rte_eth_allmulticast_disable()
return value from void to int and return negative errno values
in case of error conditions.
Modify usage of these functions across the ethdev according
to new return type.

Signed-off-by: Ivan Ilchenko <ivan.ilchenko@oktetlabs.ru>
Signed-off-by: Andrew Rybchenko <arybchenko@solarflare.com>