[media] rcar_vin: use proper name for the R-Car SoC

It is 'R-Car', not 'RCar'. No code or binding changes, only descriptive text.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.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>

Documentation/devicetree/bindings/media/rcar_vin.txt

-Renesas RCar Video Input driver (rcar_vin)
-------------------------------------------
+Renesas R-Car Video Input driver (rcar_vin)
+-------------------------------------------
 
 The rcar_vin device provides video input capabilities for the Renesas R-Car
 family of devices. The current blocks are always slaves and suppot one input