iommu: constify fwnode in iommu_ops_from_fwnode()

Make pointer to fwnode_handle a pointer to const for code safety.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240216144027.185959-3-krzysztof.kozlowski@linaro.org


Signed-off-by: Joerg Roedel <jroedel@suse.de>