network_manager_main: Use logging classes up front

This makes them accessible throughout the file and disambiguates what
can propagate from the phosphor::logging namespace.

Tested:
    Compiles as expected.

Change-Id: I36a6407e4313c8c2436e7cd3efd8c99ca385882e
Signed-off-by: William A. Kennington III <wak@google.com>
1 file changed