dt-bindings: arm: sunxi: Fix incorrect '-' usage

Commit 6bc6bf8a ("dt-bindings: arm: sunxi: document Anbernic RG35XX
handheld gaming device variants") mistakenly added '-' on each line
which created empty (i.e. description only) schemas matching anything.
This causes validation to fail on all the root node compatibles as
there are multiple oneOf clauses passing.

Fixes: 6bc6bf8a

 ("dt-bindings: arm: sunxi: document Anbernic RG35XX handheld gaming device variants")
Reviewed-by: Ryan Walklin <ryan@testtoast.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240503154402.967632-1-robh@kernel.org
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>