The rockchip iommu driver references its of_device_id table
from the init function, which fails to build when the table
is undefined:
iommu/rockchip-iommu.c: In function 'rk_iommu_init':
iommu/rockchip-iommu.c:1029:35: error: 'rk_iommu_dt_ids' undeclared (first use in this function)
np = of_find_matching_node(NULL, rk_iommu_dt_ids);
This removes the #ifdef and the corresponding of_match_ptr wrapper
to make it build both with CONFIG_OF enabled or disabled.