ethernet_interface: Fix link local autoconfiguration functionality

When this option "default-link-local-autoconf" be enabled by default,
that will enable link local autoconfiguration feature. However, seems
the logical is mismatch in EthernetInterface::originIsManuallyAssigned.
Fix the logical to match code with option for correct functionality.

Change-Id: I5a4493d1230caef60031e7b366bc41da7b5e82f4
Signed-off-by: Tim Lee <timlee660101@gmail.com>
1 file changed