libcamera: framebuffer: Add offset to FrameBuffer::Plane

This adds offset to FrameBuffer::Plane. It enables representing frame
buffers that store planes in the same dmabuf at different offsets, as
for instance required by the V4L2 NV12 pixel format.

Signed-off-by: Hirokazu Honda <hiroh@chromium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

include/libcamera/framebuffer.h

@@ -42,6 +42,7 @@ class FrameBuffer final : public Extensible
 public:
 	struct Plane {
 		FileDescriptor fd;
+		unsigned int offset;
 		unsigned int length;
 	};