[GFS2] Tidy up dir code as per Christoph Hellwig's comments

1. Comment whitespace fix
2. Removed unused header files from dir.c
3. Split the gfs2_dir_get_buffer() function into two functions

Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
index c772311..68bc3be 100644
--- a/fs/gfs2/bmap.c
+++ b/fs/gfs2/bmap.c
@@ -111,7 +111,7 @@
 		if (isdir) {
 			block = gfs2_alloc_meta(ip);
 
-			error = gfs2_dir_get_buffer(ip, block, 1, &bh);
+			error = gfs2_dir_get_new_buffer(ip, block, &bh);
 			if (error)
 				goto out_brelse;
 			gfs2_buffer_copy_tail(bh,