[FS#966] ar71xx: images are not named to their board_names

[LEDE Bugs]

The following task has a new comment added:

FS#966 - ar71xx: images are not named to their board_names
User who did this - Alexander Couzens (lynxis)

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So we have:
- image profile (the filename is based of)
- machine name (the kernel depends on this)
- board_name (user space depends of)
Did I missed a type?

IMHO if the image needs to be different (because of some magics), it should have it's own board_name.

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More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=966#comment3250