[FS#986] ARV752DPW missing default switch config

[LEDE Bugs]

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FS#986 - ARV752DPW missing default switch config
User who did this: Mathias Kresin (mkresin)
Summary: Switch "unkown structure" on ARV752DPW, switch not initialized -> ARV752DPW missing default switch config

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https://bugs.lede-project.org/index.php?do=details&task_id=986