win32: DeviceLister: always use the wide chars API

The use of FromWide and L'\\' already implied it was the case.
9 jobs for master in 11 minutes and 52 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Build
passed #265606
amd64 debian
build:linux

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passed #265607
win32
build:win32

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passed #265608
win64
build:win64

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  Unit Tests
passed #265609
amd64 debian
unit-tests:linux

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passed #265610
win32
unit-tests:win32

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passed #265611
win64
unit-tests:win64

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  Functional Tests
passed #265612
amd64 debian
functional-tests:linux

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passed #265613
win32
functional-tests:win32

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passed #265614
win64
functional-tests:win64

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