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.

Link: https://lore.kernel.org/r/20240208105314.129095-1-krzysztof.kozlowski@linaro.orgSigned-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>