ARM: cache: fix uninitialized ptr in tauros2_init

init the variable "mode" to NULL to ensure the later NULL checking is
taking effect.
Signed-off-by: NChao Xie <xiechao.mail@gmail.com>
Signed-off-by: NHaojian Zhuang <haojian.zhuang@gmail.com>

arch/arm/mm/cache-tauros2.c

@@ -192,7 +192,7 @@ static inline void __init write_actlr(u32 actlr)
 void __init tauros2_init(void)
 {
 	extern int processor_id;
-	char *mode;
+	char *mode = NULL;
 
 	disable_l2_prefetch();