drivers: ethernet: lan9250: cleanup some un-needed code

From the prior change b38a46badea27f66bba4e6b8923d6a812c14f74e adding
in the mac configuration in the device tree it is appropriate to
remove the local mac address bindings. This is done in this commit.

There is no intended functional change

Signed-off-by: Charles Hardin <ckhardin@gmail.com>