iommu: Cleanup comments for dev_enable/disable_feat

The dev_enable/disable_feat ops have been removed by commit
<f984fb09e60e> ("iommu: Remove iommu_dev_enable/disable_feature()").
Cleanup the comments to make the code clean.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20250430025249.2371751-1-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

Author: LuBaolu

include/linux/iommu.h

@@ -590,8 +590,6 @@ iommu_copy_struct_from_full_user_array(void *kdst, size_t kdst_entry_size,
  * @of_xlate: add OF master IDs to iommu grouping
  * @is_attach_deferred: Check if domain attach should be deferred from iommu
  *                      driver init to device driver init (default no)
- * @dev_enable/disable_feat: per device entries to enable/disable
- *                               iommu specific features.
  * @page_response: handle page request response
  * @def_domain_type: device default domain type, return value:
  *		- IOMMU_DOMAIN_IDENTITY: must use an identity domain