cpu: Move exception_index field from CPU_COMMON to CPUState

Signed-off-by: Andreas Färber <afaerber@suse.de>
diff --git a/target-microblaze/op_helper.c b/target-microblaze/op_helper.c
index b70b2ea..318185a 100644
--- a/target-microblaze/op_helper.c
+++ b/target-microblaze/op_helper.c
@@ -95,7 +95,9 @@
 
 void helper_raise_exception(CPUMBState *env, uint32_t index)
 {
-    env->exception_index = index;
+    CPUState *cs = CPU(mb_env_get_cpu(env));
+
+    cs->exception_index = index;
     cpu_loop_exit(env);
 }