kernelconfig_penguin
default or selected kernelversion does not have config value CONFIG_ATH9K_MAC_DEBUG.
Result is shown for kernelversion 3.9.9

Atheros MAC statistics

configname: CONFIG_ATH9K_MAC_DEBUG

Linux Kernel Configuration
└─> Device Drivers
└─> Network device support
└─> Wireless LAN
└─> Atheros Wireless Cards
└─> Atheros MAC statistics

This option enables collection of statistics for Rx/Tx status
data and some other MAC related statistics