Revert "block: add __init to blkcg_policy_register"

This reverts commit a2d445d440003f2d70ee4cd4970ea82ace616fee.

The original commit is buggy, we do use the registration functions
at runtime for modular builds.
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index 1c401b0..d3fd7aa 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -146,7 +146,7 @@
 void blkcg_exit_queue(struct request_queue *q);
 
 /* Blkio controller policy registration */
-int __init blkcg_policy_register(struct blkcg_policy *pol);
+int blkcg_policy_register(struct blkcg_policy *pol);
 void blkcg_policy_unregister(struct blkcg_policy *pol);
 int blkcg_activate_policy(struct request_queue *q,
 			  const struct blkcg_policy *pol);
@@ -577,7 +577,7 @@
 static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
 static inline void blkcg_drain_queue(struct request_queue *q) { }
 static inline void blkcg_exit_queue(struct request_queue *q) { }
-static inline int __init blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
+static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
 static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { }
 static inline int blkcg_activate_policy(struct request_queue *q,
 					const struct blkcg_policy *pol) { return 0; }