Fix #475 - Remove redundant call to ToString() in Device Service

[kbeaugrand]

Description

What's new?

• Fix Fix code scanning alert - Redundant ToString() call #475

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• Tests
• Other

[codecov]

Codecov Report

Merging #476 (7070bdd) into main (4fd449f) will decrease coverage by 0.44%.
The diff coverage is 100.00%.

❗ Current head 7070bdd differs from pull request most recent head d98ed27. Consider uploading reports for the commit d98ed27 to get more accurate results

@@            Coverage Diff             @@
##             main     #476      +/-   ##
==========================================
- Coverage   60.52%   60.08%   -0.45%     
==========================================
  Files         114      114              
  Lines        3701     3685      -16     
==========================================
- Hits         2240     2214      -26     
- Misses       1461     1471      +10     

Impacted Files	Coverage Δ
...zureIoTHub.Portal/Server/Services/DeviceService.cs	90.60% <100.00%> (ø)
...al/Client/Validators/LoRaDeviceDetailsValidator.cs	0.00% <0.00%> (-100.00%)	⬇️
...Portal/Client/Pages/Devices/DeviceDetailPage.razor	0.00% <0.00%> (ø)
.../Client/Pages/Devices/LoRaWAN/EditLoraDevice.razor	0.00% <0.00%> (ø)
...lient/Pages/Devices/LoRaWAN/CreateLoraDevice.razor	0.00% <0.00%> (ø)

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