ARM: dts: Include R-Car Gen2 product name in DTSI files

Improve the user friendliness of the DTS code base by including the
R-Car product name in each R-Car Gen2 DTSI file.

The product names are taken from:
Documentation/devicetree/bindings/arm/shmobile.txt

Signed-off-by: Magnus Damm <damm@opensource.se>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>