Tell phosphor-logging about the sw-mgr error yaml

This needs to be done so phosphor-logging will know to grab
the error log's metadata from the journal and add it to
the log in the AdditionalData field.

Tested: Check that the errors now show up in the elog-lookup.cpp
        file generated during the build by phosphor-logging.

Change-Id: I59e357986ac56ea752c9f7241a5138eb4985ceb6
Signed-off-by: Matt Spinler <spinler@us.ibm.com>