xen/pvh: Fix misplaced kfree from xlated_setup_gnttab_pages

Passing a freed 'pages' to free_xenballooned_pages will end badly
on kernels with slub debug enabled.

This looks out of place between the rc assign and the check, but
we do want to kfree pages regardless of which path we take.
Signed-off-by: Dave Jones <davej@fedoraproject.org>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

arch/x86/xen/grant-table.c

@@ -162,14 +162,15 @@ static int __init xlated_setup_gnttab_pages(void)
 	rc = arch_gnttab_map_shared(pfns, nr_grant_frames, nr_grant_frames,
 				    &xen_auto_xlat_grant_frames.vaddr);
 
-	kfree(pages);
 	if (rc) {
 		pr_warn("%s Couldn't map %ld pfns rc:%d\n", __func__,
 			nr_grant_frames, rc);
 		free_xenballooned_pages(nr_grant_frames, pages);
+		kfree(pages);
 		kfree(pfns);
 		return rc;
 	}
+	kfree(pages);
 
 	xen_auto_xlat_grant_frames.pfn = pfns;
 	xen_auto_xlat_grant_frames.count = nr_grant_frames;