KVM: define hwpoison variables static

They are not used outside of the file.
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

virt/kvm/kvm_main.c

@@ -93,8 +93,8 @@ static bool kvm_rebooting;
 
 static bool largepages_enabled = true;
 
-struct page *hwpoison_page;
-pfn_t hwpoison_pfn;
+static struct page *hwpoison_page;
+static pfn_t hwpoison_pfn;
 
 inline int kvm_is_mmio_pfn(pfn_t pfn)
 {