ethernet_interface: cleanup whitespace in logging
ethernet_interface: cleanup whitespace in logging

The log contains a fair amount of extra whitespace,
which this addresses.

Change-Id: I08a954665803cf9096fe6f3d7539e9e7818b70fa
Signed-off-by: Patrick Venture <36c53fa43f47f3fd67cb2fc38031827244d18a1f@google.com>

openbmc/phosphor-networkd,openbmc/phosphor-networkd