[media] Add missing slab.h to fix linux-next compile errors

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Reported-by: Randy Dunlap <rdunlap@xenotime.net>
Acked-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/radio/radio-aztech.c b/drivers/media/radio/radio-aztech.c
index 8117fdf..177bcbd 100644
--- a/drivers/media/radio/radio-aztech.c
+++ b/drivers/media/radio/radio-aztech.c
@@ -21,6 +21,7 @@
 #include <linux/delay.h>	/* udelay			*/
 #include <linux/videodev2.h>	/* kernel radio structs		*/
 #include <linux/io.h>		/* outb, outb_p			*/
+#include <linux/slab.h>
 #include <media/v4l2-device.h>
 #include <media/v4l2-ioctl.h>
 #include <media/v4l2-ctrls.h>