dt-bindings: power: renesas,rcar-sysc: correct typo in path

Fix typo '.' -> '/' in the path to headers.

Fixes: 981a3405 ("dt-bindings: power: renesas,rcar-sysc: drop useless consumer example")
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220411095317.221317-1-krzysztof.kozlowski@linaro.org