iommu/arm-smmu: fix possible null-ptr-deref in arm_smmu_device_probe()

In the Linux kernel, the following vulnerability has been resolved: iommu/arm-smmu: fix possible null-ptr-deref in arm_smmu_device_probe() It will cause null-ptr-deref when using 'res', if platform_get_resource() returns NULL, so move using 'res' after devm_ioremap_resource() that will check it to avoid null-ptr-deref. And use devm_platform_get_and_ioremap_resource() to simplify code.