OSDOCS-20054: Remove invalid amd_iommu=on kernel argument

[dwivedipranav-dev]

Summary

• Removes the incorrect instruction to set amd_iommu=on in the IOMMU MachineConfig procedure.
• Clarifies that AMD IOMMU is enabled by default when AMD-Vi is enabled in BIOS; intel_iommu=on remains valid for Intel.
• Updates modules/virt-adding-kernel-arguments-enable-iommu.adoc (used by PCI passthrough and vGPU).
  Jira: https://issues.redhat.com/browse/OSDOCS-20054

Cherry-picks

Please cherry-pick to: enterprise-4.16, enterprise-4.17, enterprise-4.18, enterprise-4.19, enterprise-4.20, enterprise-4.21, enterprise-4.22

Test plan

• Preview the PCI passthrough and vGPU assemblies
• Confirm the Intel example still uses intel_iommu=on
• Confirm this module no longer recommends amd_iommu=on
• SME review of optional iommu=pt wording

[openshift-ci-robot]

@dwivedipranav-dev: This pull request references OSDOCS-20054 which is a valid jira issue.

Warning: The referenced jira issue has an invalid target version for the target branch this PR targets: expected the bug to target the "5.1.0" version, but no target version was set.

Details

In response to this:

Summary

• Removes the incorrect instruction to set amd_iommu=on in the IOMMU MachineConfig procedure.
• Clarifies that AMD IOMMU is enabled by default when AMD-Vi is enabled in BIOS; intel_iommu=on remains valid for Intel.
• Updates modules/virt-adding-kernel-arguments-enable-iommu.adoc (used by PCI passthrough and vGPU).
  Jira: https://issues.redhat.com/browse/OSDOCS-20054

Cherry-picks

Please cherry-pick to: enterprise-4.16, enterprise-4.17, enterprise-4.18, enterprise-4.19, enterprise-4.20, enterprise-4.21, enterprise-4.22

Test plan

• Preview the PCI passthrough and vGPU assemblies
• Confirm the Intel example still uses intel_iommu=on
• Confirm this module no longer recommends amd_iommu=on
• SME review of optional iommu=pt wording

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[openshift-ci]

Hi @dwivedipranav-dev. Thanks for your PR.

I'm waiting for a openshift member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work.

Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

Details

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.