external/audiocodec: fix make clean
external/audiocodec: fix make clean

sub directory objects are not cleaned after make clean

Steps:
./configure.sh /artik055s/audio
make
make clean
find . -name "*.o"

Signed-off-by: Manohara HK <02db916c8fbcb3f412fbcb70556ea7b9f661857a@samsung.com>

pillip8282/TizenRT,HONGCHAEHEE/TizenRT,chanijjani/TizenRT,jeongchanKim/TizenRT,jsdosa/TizenRT,chanijjani/TizenRT,JeonginKim/TizenRT,jeongarmy/TizenRT,davidfather/TizenRT,pillip8282/TizenRT,jsdosa/TizenRT,junmin-kim/TizenRT,junmin-kim/TizenRT,Samsung/TizenRT,jeongarmy/TizenRT,junmin-kim/TizenRT,an4967/TizenRT,HONGCHAEHEE/TizenRT,jsdosa/TizenRT,davidfather/TizenRT,HONGCHAEHEE/TizenRT,jsdosa/TizenRT,chanijjani/TizenRT,jsdosa/TizenRT,Samsung/TizenRT,an4967/TizenRT,JeonginKim/TizenRT,jsdosa/TizenRT,chanijjani/TizenRT,jeongchanKim/TizenRT,sunghan-chang/TizenRT,JeonginKim/TizenRT,Samsung/TizenRT,JeonginKim/TizenRT,sunghan-chang/TizenRT,junmin-kim/TizenRT,Samsung/TizenRT,pillip8282/TizenRT,sunghan-chang/TizenRT,pillip8282/TizenRT,an4967/TizenRT,an4967/TizenRT,HONGCHAEHEE/TizenRT,Samsung/TizenRT,jeongchanKim/TizenRT,jeongarmy/TizenRT,jeongchanKim/TizenRT,sunghan-chang/TizenRT,davidfather/TizenRT,davidfather/TizenRT,pillip8282/TizenRT,chanijjani/TizenRT,chanijjani/TizenRT,sunghan-chang/TizenRT,jeongarmy/TizenRT,davidfather/TizenRT,jeongarmy/TizenRT,davidfather/TizenRT,an4967/TizenRT,an4967/TizenRT,junmin-kim/TizenRT,pillip8282/TizenRT,jsdosa/TizenRT,sunghan-chang/TizenRT,HONGCHAEHEE/TizenRT,jeongchanKim/TizenRT,jeongarmy/TizenRT,an4967/TizenRT,Samsung/TizenRT,davidfather/TizenRT,JeonginKim/TizenRT,Samsung/TizenRT,HONGCHAEHEE/TizenRT,jeongarmy/TizenRT,junmin-kim/TizenRT,jeongchanKim/TizenRT,JeonginKim/TizenRT,sunghan-chang/TizenRT,jeongchanKim/TizenRT,chanijjani/TizenRT,pillip8282/TizenRT,junmin-kim/TizenRT