iommu/rockchip: Fix build without CONFIG_OF

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.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 425061b0f5074 ("iommu/rockchip: Play nice in multi-platform builds")
Reviewed-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Joerg Roedel <jroedel@suse.de>