check_source.sh: fix sed error: -e expression #1, char 25: Invalid range end

Warning happen only if old sed (4.4) is used.

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[TOPOLOGY]

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NetName=None

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Nodes=0x01

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Node64Present=0x01

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Node64Name=micromod

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Node64DCFName=PEAK MicroMod.eds

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EDSBaseName=eds