[media] v4l2-mem2mem: add support for prepare_buf

This was never added for some reason, so add it now.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
diff --git a/include/media/v4l2-mem2mem.h b/include/media/v4l2-mem2mem.h
index c5f3914..3bbd96d 100644
--- a/include/media/v4l2-mem2mem.h
+++ b/include/media/v4l2-mem2mem.h
@@ -116,6 +116,8 @@
 		  struct v4l2_buffer *buf);
 int v4l2_m2m_dqbuf(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
 		   struct v4l2_buffer *buf);
+int v4l2_m2m_prepare_buf(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
+			 struct v4l2_buffer *buf);
 int v4l2_m2m_create_bufs(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
 			 struct v4l2_create_buffers *create);
 
@@ -248,6 +250,8 @@
 				struct v4l2_buffer *buf);
 int v4l2_m2m_ioctl_dqbuf(struct file *file, void *fh,
 				struct v4l2_buffer *buf);
+int v4l2_m2m_ioctl_prepare_buf(struct file *file, void *fh,
+			       struct v4l2_buffer *buf);
 int v4l2_m2m_ioctl_streamon(struct file *file, void *fh,
 				enum v4l2_buf_type type);
 int v4l2_m2m_ioctl_streamoff(struct file *file, void *fh,