examples/wave_gen: fix Kconfig to prevent invalied enable
examples/wave_gen: fix Kconfig to prevent invalied enable

wave_gen can be enabled when CONFIG_AUDIO=y

Change-Id: I01f38fedf3e23c358cf01d80594a79e324fe845f
Signed-off-by: Bongryul Lee <40e5879ba2a710c5c582426d4fb9229bced4a8b1@samsung.com>

JunhwanPark/TizenRT,JunhwanPark/TizenRT,JunhwanPark/TizenRT,JunhwanPark/TizenRT,JunhwanPark/TizenRT,JunhwanPark/TizenRT