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/delayed-inode.c b/fs/btrfs/delayed-inode.c
index 76e85d6..33e561a 100644
--- a/fs/btrfs/delayed-inode.c
+++ b/fs/btrfs/delayed-inode.c
@@ -1318,10 +1318,10 @@
 struct btrfs_async_delayed_work {
 	struct btrfs_delayed_root *delayed_root;
 	int nr;
-	struct btrfs_work_struct work;
+	struct btrfs_work work;
 };
 
-static void btrfs_async_run_delayed_root(struct btrfs_work_struct *work)
+static void btrfs_async_run_delayed_root(struct btrfs_work *work)
 {
 	struct btrfs_async_delayed_work *async_work;
 	struct btrfs_delayed_root *delayed_root;