kasan: use -EOPNOTSUPP on xen

Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>

kasan.c

diff --git a/kasan.c b/kasan.c
index a07fbcd..0a68c15 100644
--- a/kasan.c
+++ b/kasan.c
@@ -19,7 +19,7 @@
 	sleep(1);
 
 	if (!is_kasan_setup())
-		return -EINVAL;
+		return -EOPNOTSUPP;
 
 	return 0;
 }