KVM: x86/mmu: Fix and clarify comments about clearing D-bit vs. write-protecting

KVM: x86/mmu: Fix and clarify comments about clearing D-bit vs. write-protecting

Drop the "If AD bits are enabled/disabled" verbiage from the comments
above kvm_tdp_mmu_clear_dirty_{slot,pt_masked}() since TDP MMU SPTEs may
need to be write-protected even when A/D bits are enabled. i.e. These
comments aren't technically correct.

No functional change intended.

Signed-off-by: David Matlack <dmatlack@google.com>
Link: https://lore.kernel.org/r/20240315230541.1635322-4-dmatlack@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>