iommu/qcom: Drop of_match_ptr to fix -Wunused-const-variable

The of_device_id is included unconditionally by of.h header and used
in the driver as well.  Remove of_match_ptr to fix W=1 compile test
warning with !CONFIG_OF:

    drivers/iommu/qcom_iommu.c:910:34: warning: 'qcom_iommu_of_match' defined but not used [-Wunused-const-variable=]
      910 | static const struct of_device_id qcom_iommu_of_match[] = {

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20200728170859.28143-3-krzk@kernel.org
Signed-off-by: Joerg Roedel <jroedel@suse.de>