completion: Drop init_completion define

Changeset cd8084f9 ("locking/lockdep: Apply crossrelease to completions")
added a CONFIG_LOCKDEP_COMPLETE (that was later renamed to
CONFIG_LOCKDEP_COMPLETIONS).

Such changeset renamed the init_completion, and add a macro
that would either run a modified version or the original code.

However, such code reported too many false positives. So, it
ended being dropped later on by
changeset e966eaee ("locking/lockdep: Remove the cross-release locking checks").

Yet, the define remained there as just:

	 #define init_completion(x) __init_completion(x)

Get rid of the define, and return __init_completion() function
to its original name.

Fixes: e966eaee ("locking/lockdep: Remove the cross-release locking checks")
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/e657bfc533545c185b1c3c55926a449ead56a88b.1606823973.git.mchehab+huawei@kernel.org

include/linux/completion.h

@@ -28,8 +28,7 @@ struct completion {
 	struct swait_queue_head wait;
 };
 
-#define init_completion_map(x, m) __init_completion(x)
-#define init_completion(x) __init_completion(x)
+#define init_completion_map(x, m) init_completion(x)
 static inline void complete_acquire(struct completion *x) {}
 static inline void complete_release(struct completion *x) {}
 
@@ -82,7 +81,7 @@ static inline void complete_release(struct completion *x) {}
  * This inline function will initialize a dynamically created completion
  * structure.
  */
-static inline void __init_completion(struct completion *x)
+static inline void init_completion(struct completion *x)
 {
 	x->done = 0;
 	init_swait_queue_head(&x->wait);