The Henninger low cost board was never sold and so had no users outside
Renesas (and Cogent Embedded). Instead Renesas has made the Porter board
which has mostly similar hardware. Now that the Porter board support is on
par with Henninger, we can remove the Henninger's device tree file.
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>