metag: add __init to metag_cache_probe()

metag_cache_probe() is only called from setup_arch(), so add the __init
attribute to it.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
diff --git a/arch/metag/mm/cache.c b/arch/metag/mm/cache.c
index b713ec0..89da74a 100644
--- a/arch/metag/mm/cache.c
+++ b/arch/metag/mm/cache.c
@@ -42,7 +42,7 @@
  * Probe the L1 cache configuration to aid the L1 physical cache flushing
  * functions.
  */
-void metag_cache_probe(void)
+void __init metag_cache_probe(void)
 {
 #ifndef CONFIG_METAG_META12
 	int coreid = metag_in32(METAC_CORE_ID);