ARM: at91/defconfig: enable CLASSD.

Enable the CLASSD audio interface available on sam9x60.

Signed-off-by: Cristian Birsan <cristian.birsan@microchip.com>

Author: cristibirsan

arch/arm/configs/at91_dt_defconfig

@@ -182,6 +182,7 @@ CONFIG_SND_SOC=y
 CONFIG_SND_ATMEL_SOC=y
 CONFIG_SND_AT91_SOC_SAM9G20_WM8731=y
 CONFIG_SND_ATMEL_SOC_WM8904=y
+CONFIG_SND_ATMEL_SOC_CLASSD=y
 CONFIG_SND_AT91_SOC_SAM9X5_WM8731=y
 CONFIG_SND_SOC_MIKROE_PROTO=m
 CONFIG_SND_MCHP_SOC_I2S_MCC=y