ASoC: update for removeal of slab.h from percpu.h

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/soc/codecs/ad193x.c

@@ -12,6 +12,7 @@
 #include <linux/device.h>
 #include <linux/i2c.h>
 #include <linux/spi/spi.h>
+#include <linux/slab.h>
 #include <sound/core.h>
 #include <sound/pcm.h>
 #include <sound/pcm_params.h>