KVM: do not release the error page

After commit a2766325cf9f9, the error page is replaced by the
error code, it need not be released anymore

[ The patch has been compiling tested for powerpc ]

Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index eafba99..a2e85af 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1186,8 +1186,9 @@
 
 void kvm_release_page_clean(struct page *page)
 {
-	if (!is_error_page(page))
-		kvm_release_pfn_clean(page_to_pfn(page));
+	WARN_ON(is_error_page(page));
+
+	kvm_release_pfn_clean(page_to_pfn(page));
 }
 EXPORT_SYMBOL_GPL(kvm_release_page_clean);