media: mx2_emmaprp: Correct return type for mem2mem buffer helpers

Fix the assigned type of mem2mem buffer handling API.
Namely, these functions:

 v4l2_m2m_next_buf
 v4l2_m2m_last_buf
 v4l2_m2m_buf_remove
 v4l2_m2m_next_src_buf
 v4l2_m2m_next_dst_buf
 v4l2_m2m_last_src_buf
 v4l2_m2m_last_dst_buf
 v4l2_m2m_src_buf_remove
 v4l2_m2m_dst_buf_remove

return a struct vb2_v4l2_buffer, and not a struct vb2_buffer.

Fixing this is necessary to fix the mem2mem buffer handling API,
changing the return to the correct struct vb2_v4l2_buffer instead
of a void pointer.
Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/platform/mx2_emmaprp.c

@@ -274,7 +274,7 @@ static void emmaprp_device_run(void *priv)
 {
 	struct emmaprp_ctx *ctx = priv;
 	struct emmaprp_q_data *s_q_data, *d_q_data;
-	struct vb2_buffer *src_buf, *dst_buf;
+	struct vb2_v4l2_buffer *src_buf, *dst_buf;
 	struct emmaprp_dev *pcdev = ctx->dev;
 	unsigned int s_width, s_height;
 	unsigned int d_width, d_height;
@@ -294,8 +294,8 @@ static void emmaprp_device_run(void *priv)
 	d_height = d_q_data->height;
 	d_size = d_width * d_height;
 
-	p_in = vb2_dma_contig_plane_dma_addr(src_buf, 0);
-	p_out = vb2_dma_contig_plane_dma_addr(dst_buf, 0);
+	p_in = vb2_dma_contig_plane_dma_addr(&src_buf->vb2_buf, 0);
+	p_out = vb2_dma_contig_plane_dma_addr(&dst_buf->vb2_buf, 0);
 	if (!p_in || !p_out) {
 		v4l2_err(&pcdev->v4l2_dev,
 			 "Acquiring kernel pointers to buffers failed\n");