KVM x86 fixes for 6.11
- Fixup missed comments from the REMOVED_SPTE=>FROZEN_SPTE rename.
- Ensure a root is successfully loaded when pre-faulting SPTEs.
- Grab kvm->srcu when handling KVM_SET_VCPU_EVENTS to guard against accessing
memslots if toggling SMM happens to force a VM-Exit.
- Emulate MSR_{FS,GS}_BASE on SVM even though interception is always disabled,
so that KVM does the right thing if KVM's emulator encounters {RD,WR}MSR.
- Explicitly clear BUS_LOCK_DETECT from KVM's caps on AMD, as KVM doesn't yet
virtualize BUS_LOCK_DETECT on AMD.
- Cleanup the help message for CONFIG_KVM_AMD_SEV, and call out that KVM now
supports SEV-SNP too.