KVM: x86/mmu: Remove is_obsolete() call

Unwinding usage of is_obsolete() is a step towards removing x86's fast
invalidate mechanism, i.e. this is one part of a revert all patches from
the series that introduced the mechanism[1].

This is a partial revert of commit 05988d72 ("KVM: MMU: reduce
KVM_REQ_MMU_RELOAD when root page is zapped").

[1] https://lkml.kernel.org/r/1369960590-14138-1-git-send-email-xiaoguangrong@linux.vnet.ibm.com

Cc: Xiao Guangrong <guangrong.xiao@gmail.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/mmu.c

@@ -2713,11 +2713,7 @@ static int kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp,
 	} else {
 		list_move(&sp->link, &kvm->arch.active_mmu_pages);
 
-		/*
-		 * The obsolete pages can not be used on any vcpus.
-		 * See the comments in kvm_mmu_invalidate_zap_all_pages().
-		 */
-		if (!sp->role.invalid && !is_obsolete_sp(kvm, sp))
+		if (!sp->role.invalid)
 			kvm_reload_remote_mmus(kvm);
 	}