riscv: dts: use capital "OR" for multiple licenses in SPDX

riscv: dts: use capital "OR" for multiple licenses in SPDX

Documentation/process/license-rules.rst and checkpatch expect the SPDX
identifier syntax for multiple licenses to use capital "OR".  Correct it
to keep consistent format and avoid copy-paste issues.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230823085238.113642-1-krzysztof.kozlowski@linaro.org
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>