net: lpc_eth: Remove unused 'pldat' variable

Since commit f786f356 ("net: ethernet: lpc_eth: use phydev
from struct net_device") the 'pldat' variable became unused, so
just remove it.

Reported-by: Olof's autobuilder <build@lixom.net>
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>