ltq-xdsl-app: drop esi call

ltq-xdsl-app: drop esi call

The esi call was added to workaround a race condition between applying
a configured mac address to the wan interface and starting the protocol
(handler) as it was observed in a DHCP over ATM bridge configuration.

Martin Schiller, TDT GmbH was so kind to test with their local
infrastructure if the race condition still exists. The provided package
dumps captured behind the DSLAM shows that it doesn't. It was most
likely fixed with adding carrier support to the lantiq ptm/atm driver.

Signed-off-by: Mathias Kresin <dev@kresin.me>