net/sfc: set multicast address list in started state only

net/sfc: set multicast address list in started state only

According to 'libefx' API requirements, one is allowed to
apply multicast address list to the port in started state
only, otherwise the new array should be copied to a local
storage in order to be applied during the next port start

Coverity issue: 141296
Fixes: 0fa0070e4391 ("net/sfc: support multicast addresses list controls")

Fixes: e9ddf37a507d ("net/sfc: fix setting empty multicast list")
Cc: stable@dpdk.org
Signed-off-by: Ivan Malov <ivan.malov@oktetlabs.ru>
Signed-off-by: Andrew Rybchenko <arybchenko@solarflare.com>
Reviewed-by: Andrew Lee <alee@solarflare.com>
Reviewed-by: Andy Moreton <amoreton@solarflare.com>