[media] media: mem2mem: make reference to struct m2m_ops in the core const

The mem2mem core doesn't change struct m2m_ops, provided by the driver,
make references to it const.
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/v4l2-core/v4l2-mem2mem.c

@@ -62,7 +62,7 @@ struct v4l2_m2m_dev {
 	struct list_head	job_queue;
 	spinlock_t		job_spinlock;
 
-	struct v4l2_m2m_ops	*m2m_ops;
+	const struct v4l2_m2m_ops *m2m_ops;
 };
 
 static struct v4l2_m2m_queue_ctx *get_queue_ctx(struct v4l2_m2m_ctx *m2m_ctx,
@@ -519,7 +519,7 @@ EXPORT_SYMBOL(v4l2_m2m_mmap);
  *
  * Usually called from driver's probe() function.
  */
-struct v4l2_m2m_dev *v4l2_m2m_init(struct v4l2_m2m_ops *m2m_ops)
+struct v4l2_m2m_dev *v4l2_m2m_init(const struct v4l2_m2m_ops *m2m_ops)
 {
 	struct v4l2_m2m_dev *m2m_dev;
 

include/media/v4l2-mem2mem.h

@@ -125,7 +125,7 @@ unsigned int v4l2_m2m_poll(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
 int v4l2_m2m_mmap(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
 		  struct vm_area_struct *vma);
 
-struct v4l2_m2m_dev *v4l2_m2m_init(struct v4l2_m2m_ops *m2m_ops);
+struct v4l2_m2m_dev *v4l2_m2m_init(const struct v4l2_m2m_ops *m2m_ops);
 void v4l2_m2m_release(struct v4l2_m2m_dev *m2m_dev);
 
 struct v4l2_m2m_ctx *v4l2_m2m_ctx_init(struct v4l2_m2m_dev *m2m_dev,