media: media videobuf2: Stop direct calls to queue num_buffers field

Use vb2_get_num_buffers() to avoid using queue num_buffers field directly.
This allows us to change how the number of buffers is computed in the
future.

Fixes: d055a76c ("media: core: Report the maximum possible number of buffers for the queue")
Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
Acked-by: Tomasz Figa <tfiga@chromium.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

drivers/media/common/videobuf2/videobuf2-core.c

@@ -989,7 +989,7 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
 	bool no_previous_buffers = !q_num_bufs;
 	int ret = 0;
 
-	if (q->num_buffers == q->max_num_buffers) {
+	if (q_num_bufs == q->max_num_buffers) {
 		dprintk(q, 1, "maximum number of buffers already allocated\n");
 		return -ENOBUFS;
 	}

drivers/media/common/videobuf2/videobuf2-v4l2.c

@@ -1029,7 +1029,7 @@ int vb2_ioctl_create_bufs(struct file *file, void *priv,
 	int res = vb2_verify_memory_type(vdev->queue, p->memory,
 			p->format.type);
 
-	p->index = vdev->queue->num_buffers;
+	p->index = vb2_get_num_buffers(vdev->queue);
 	fill_buf_caps(vdev->queue, &p->capabilities);
 	validate_memory_flags(vdev->queue, p->memory, &p->flags);
 	/*