This patch addresses a few problems with the commit:
"ath6kl: Implement support for listen interval from userspace"
* The debugfs file required for reading/writing the listen interval
wasn't created. Fix this.
* The interface index was being hardcoded to zero. Fix this.
* Two separate parameters, "listen_interval_time and listen_interval_beacons"
were being used. This fails to work as expected because the FW assigns
higher precedence to "listen_interval_beacons" and "listen_interval_time"
ends up being never used at all.
To handle this, fix the host driver to exclusively use listen interval
based on units of beacon intervals.
To set the listen interval, a user would now do something like this: