Provide a MappedFrameBuffer helper class which will map
all of the Planes within a FrameBuffer and provide CPU addressable
pointers for those planes.
The MappedFrameBuffer implements the interface of the MappedBuffer
allowing other buffer types to be constructed of the same form, with a
common interface and cleanup.
This allows MappedBuffer instances to be created from Camera3Buffer types.
Mappings are removed upon destruction.
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
