fwts: missing field names from fwts --log-fields (regression)

Removing the --lp-tags broke --log-fields, discovered when running the fwts-test regression tests.

 I forgot to remove the LOG_TAG field when I removed the --lp-tags and --lp-tags-log options. The downside is that this breaks the --log-fields option as this now can't find the tag bitfield and exits prematurely, so we originally had the following fields output:

    RES,ERR,WRN,DBG,INF,SUM,SEP,NLN,ADV,HED,TAG,PAS,FAL,SKP,ABT,INO

The broken result is now:

    RES,ERR,WRN,DBG,INF,SUM,SEP,NLN,ADV,HED

..and should be:

    RES,ERR,WRN,DBG,INF,SUM,SEP,NLN,ADV,HED,PAS,FAL,SKP,ABT,INO