dt-bindings: pwm: renesas: pwm-rcar: Document R8A779{7|8}0 bindings

Document the R-Car V3{M|H} (R8A779{7|8}0) SoC in the  Renesas R-Car PWM
bindings. R8A77970's hardware is a generic R-Car gen3 PWM, while R8A77980
has an extra error injection register...
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

Documentation/devicetree/bindings/pwm/renesas,pwm-rcar.txt

@@ -12,6 +12,8 @@ Required Properties:
  - "renesas,pwm-r8a7795": for R-Car H3
  - "renesas,pwm-r8a7796": for R-Car M3-W
  - "renesas,pwm-r8a77965": for R-Car M3-N
+ - "renesas,pwm-r8a77970": for R-Car V3M
+ - "renesas,pwm-r8a77980": for R-Car V3H
  - "renesas,pwm-r8a77990": for R-Car E3
  - "renesas,pwm-r8a77995": for R-Car D3
 - reg: base address and length of the registers block for the PWM.