dmaengine: idxd: Remove unnecessary IOMMU_DEV_FEAT_IOPF

dmaengine: idxd: Remove unnecessary IOMMU_DEV_FEAT_IOPF

The IOMMU_DEV_FEAT_IOPF implementation in the iommu driver is just a no-op.
It will also be removed from the iommu driver in the subsequent patch.
Remove it to avoid dead code.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Acked-by: Vinod Koul <vkoul@kernel.org>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Fenghua Yu <fenghuay@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Yi Liu <yi.l.liu@intel.com>
Tested-by: Zhangfei Gao <zhangfei.gao@linaro.org>
Link: https://lore.kernel.org/r/20250418080130.1844424-6-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>