KVM: SVM: Remove wbinvd in sev_vm_destroy()

KVM: SVM: Remove wbinvd in sev_vm_destroy()

Before sev_vm_destroy() is called, kvm_arch_guest_memory_reclaimed()
has been called for SEV and SEV-ES and kvm_arch_gmem_invalidate()
has been called for SEV-SNP. These functions have already handled
flushing the memory. Therefore, this wbinvd_on_all_cpus() can
simply be dropped.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Zheyun Shen <szy0127@sjtu.edu.cn>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lore.kernel.org/r/20250522233733.3176144-7-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>