[FS#404] lede-ipq806x-R7500

[LEDE Bugs]

The following task has a new comment added:

FS#404 - lede-ipq806x-R7500
User who did this - john (john)

----------
this probably needs a similar fix to what this PR does

https://github.com/lede-project/source/pull/713

could you try adding the r7500 to the switch statement please
----------

More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=404#comment1299