dell-precision-5560: remove redundant config and enable fwupd

[matdibu]

Description of changes

• removed redundant i915.modeset=1
• enabled services.fwupd

Things done

• Tested the changes in your own NixOS Configuration
• Tested the changes end-to-end by using your fork of nixos-hardware and
  importing it via <nixos-hardware> or Flake input

[Mic92]

@mergify queue

[Mic92]

@Lassulus I think you also disabled mergify in other repositories. Can you only exclude nixpkgs instead?

[Lassulus]

@Lassulus I think you also disabled mergify in other repositories. Can you only exclude nixpkgs instead?

done, unsuspended mergify again and removed access from nixpgs