enip/detect: remove double registration of enip_command keyword

[catenacyber]

Link to ticket: https://redmine.openinfosecfoundation.org/issues/
https://redmine.openinfosecfoundation.org/issues/3958 follow up

Describe changes:

• enip/detect: remove double registration of enip_command keyword

credits to @regit for finding it

(must have come from some git rebase)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.72%. Comparing base (37fa2a6) to head (a0201f6).
Report is 14 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #11981      +/-   ##
==========================================
- Coverage   82.77%   82.72%   -0.06%     
==========================================
  Files         910      910              
  Lines      249016   249000      -16     
==========================================
- Hits       206134   205983     -151     
- Misses      42882    43017     +135     

Flag	Coverage Δ
fuzzcorpus	60.80% <ø> (+0.03%)	⬆️
livemode	18.70% <ø> (-0.01%)	⬇️
pcap	44.06% <ø> (-0.03%)	⬇️
suricata-verify	62.23% <ø> (+0.04%)	⬆️
unittests	59.01% <ø> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

[suricata-qa]

Information: QA ran without warnings.

Pipeline 23124

[victorjulien]

Merged in #12004, thanks!