[FS#373] ath9k: high load >10

[LEDE Bugs]

The following task has a new comment added:

FS#373 - ath9k: high load >10
User who did this - Bastian Bittorf (bittorf)

----------
what i also detected is, that sometimes the counters in /proc/interrupts are
stopping for some (e.g. 20) minutes and ofcourse wifi hangs during this period.

when debugging this with

echo 0x4409 >/sys/kernel/debug/ieee80211/phy0/ath9k/debug

i can see a lot of hangs and resets (~once per second)
----------

More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=373#comment1216