dt-bindings: arm: renesas: Fix SoC mismatch for Stout

make dtbs_check:

    arch/arm/boot/dts/r8a7790-stout.dt.yaml: compatible: ['renesas,stout', 'renesas,r8a7790'] is not valid under any of the given schemas

The Stout development board has an R-Car H2 (r8a7790) SoC, not an R-Car
H1 (r8a7779).

Fixes: 12749350 ("dt-bindings: arm: Convert Renesas board/soc bindings to json-schema")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>