[media] dt-bindings: Add Renesas R-Car FCP DT bindings

The FCP is a companion module of video processing modules in the Renesas
R-Car Gen3 SoCs. It provides data compression and decompression, data
caching, and conversion of AXI transactions in order to reduce the
memory bandwidth.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>