kernelconfig_penguin
default or selected kernelversion does not have config value CONFIG_ATH9K_RATE_CONTROL.
Result is shown for kernelversion 3.9.6

Atheros ath9k rate control

configname: CONFIG_ATH9K_RATE_CONTROL

Linux Kernel Configuration
└─> Device Drivers
└─> Network device support
└─> Wireless LAN
└─> Atheros Wireless Cards
└─> Atheros ath9k rate control

Say Y, if you want to use the ath9k specific rate control
module instead of minstrel_ht.