[FS#341] ath10k-firmware Makefile references non-existent QCA9887_BOARD_FILE_MD5 and QCA9887_FIRMWARE_FILE_MD

[LEDE Bugs]

The following task has a new comment added:

FS#341 - ath10k-firmware Makefile references non-existent QCA9887_BOARD_FILE_MD5 and QCA9887_FIRMWARE_FILE_MD
User who did this - Felix Fietkau (nbd)

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Fix pushed in 87b074726, thanks.
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More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=341#comment1065