std::reverse_iterator<iterator> is constructed from an instance of
iterator, and automatically subtracts 1 when dereferencing. rbegin() and
rend() should thus be constructed from end() and begin() respectively.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>