fs_enet: restore promiscuous and multicast settings in restart()

The restart() function is called when the link state changes and resets
multicast and promiscuous settings. This patch restores those settings at the
end of restart().

Signed-off-by: Laurent Pinchart <laurentp@cse-semaphore.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>