bcachefs: count_event()

Small helper for event counters.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
diff --git a/fs/bcachefs/alloc_background.c b/fs/bcachefs/alloc_background.c
index ccc3779..6e719dd 100644
--- a/fs/bcachefs/alloc_background.c
+++ b/fs/bcachefs/alloc_background.c
@@ -1674,7 +1674,7 @@ static int bch2_discard_one_bucket(struct btree_trans *trans,
 	if (ret)
 		goto out;
 
-	this_cpu_inc(c->counters[BCH_COUNTER_bucket_discard]);
+	count_event(c, bucket_discard);
 	(*discarded)++;
 out:
 	(*seen)++;