media: dt-bindings: media: rcar_vin: add device tree support for r8a774[35]

Add compatible strings for r8a7743 and r8a7745. No driver change
is needed as "renesas,rcar-gen2-vin" will activate the right code.
However, it is good practice to document compatible strings for the
specific SoC as this allows SoC specific changes to the driver if
needed, in addition to document SoC support and therefore allow
checkpatch.pl to validate compatible string values.

Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Reviewed-by: Biju Das <biju.das@bp.renesas.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>