btrfs: Cleanup the "_struct" suffix in btrfs_workequeue

Since the "_struct" suffix is mainly used for distinguish the differnt
btrfs_work between the original and the newly created one,
there is no need using the suffix since all btrfs_workers are changed
into btrfs_workqueue.

Also this patch fixed some codes whose code style is changed due to the
too long "_struct" suffix.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Tested-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fb.com>
diff --git a/fs/btrfs/reada.c b/fs/btrfs/reada.c
index 9e01d36..30947f9 100644
--- a/fs/btrfs/reada.c
+++ b/fs/btrfs/reada.c
@@ -91,8 +91,7 @@
 };
 
 struct reada_machine_work {
-	struct btrfs_work_struct
-				work;
+	struct btrfs_work	work;
 	struct btrfs_fs_info	*fs_info;
 };
 
@@ -734,7 +733,7 @@
 
 }
 
-static void reada_start_machine_worker(struct btrfs_work_struct *work)
+static void reada_start_machine_worker(struct btrfs_work *work)
 {
 	struct reada_machine_work *rmw;
 	struct btrfs_fs_info *fs_info;