enip: remove unnecessary unsafe

[catenacyber]

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

Describe changes:

• enip: remove unnecessary unsafe to make cargo update on MSRV happy

error: unnecessary `unsafe` block
   --> src/enip/enip.rs:637:9
    |
585 | pub unsafe extern "C" fn SCEnipRegisterParsers() {
    | ------------------------------------------------ because it's nested under this `unsafe` fn
...
637 |         unsafe {
    |         ^^^^^^ unnecessary `unsafe` block
    |

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.45%. Comparing base (f0dbfe8) to head (f47ac2b).

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #11290      +/-   ##
==========================================
- Coverage   82.45%   82.45%   -0.01%     
==========================================
  Files         961      961              
  Lines      251710   251708       -2     
==========================================
- Hits       207552   207536      -16     
- Misses      44158    44172      +14     

Flag	Coverage Δ
fuzzcorpus	60.30% <100.00%> (-0.01%)	⬇️
livemode	18.68% <100.00%> (-0.01%)	⬇️
pcap	43.76% <0.00%> (-0.03%)	⬇️
suricata-verify	61.16% <100.00%> (-0.02%)	⬇️
unittests	59.96% <100.00%> (-0.01%)	⬇️

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

[suricata-qa]

Information:

ERROR: QA failed on SURI_TLPW2_autofp_suri_time.

ERROR: QA failed on SURI_TLPR1_suri_time.

field	baseline	test	%
	SURI_TLPW2_autofp_stats_chk
.uptime	137	144	105.11%
	SURI_TLPR1_stats_chk
.uptime	642	688	107.17%

Pipeline 21061

[victorjulien]

Merged in #11309, thanks!