For code safety, constify pointers to data which is not modified.

Link: https://lore.kernel.org/r/20220623102432.108059-3-krzysztof.kozlowski@linaro.orgReviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>