media: rockchip/rga: 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/rockchip/rga/rga.c

@@ -43,7 +43,7 @@ static void device_run(void *prv)
 {
 	struct rga_ctx *ctx = prv;
 	struct rockchip_rga *rga = ctx->rga;
-	struct vb2_buffer *src, *dst;
+	struct vb2_v4l2_buffer *src, *dst;
 	unsigned long flags;
 
 	spin_lock_irqsave(&rga->ctrl_lock, flags);
@@ -53,8 +53,8 @@ static void device_run(void *prv)
 	src = v4l2_m2m_next_src_buf(ctx->fh.m2m_ctx);
 	dst = v4l2_m2m_next_dst_buf(ctx->fh.m2m_ctx);
 
-	rga_buf_map(src);
-	rga_buf_map(dst);
+	rga_buf_map(&src->vb2_buf);
+	rga_buf_map(&dst->vb2_buf);
 
 	rga_hw_start(rga);