[GFS2] Tidy gfs2_unstuffer_page

Tidy up gfs2_unstuffer_page by:

 a) Moving it into bmap.c
 b) Making it static
 c) Calling it directly from gfs2_unstuff_dinode
 d) Updating all callers of gfs2_unstuff_dinode due to one less
    required argument.

It doesn't change the behaviour at all.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
diff --git a/fs/gfs2/ops_address.c b/fs/gfs2/ops_address.c
index d33f6aa..93e00a8 100644
--- a/fs/gfs2/ops_address.c
+++ b/fs/gfs2/ops_address.c
@@ -395,8 +395,7 @@
 
 	if (gfs2_is_stuffed(ip)) {
 		if (end > sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode)) {
-			error = gfs2_unstuff_dinode(ip, gfs2_unstuffer_page,
-						    page);
+			error = gfs2_unstuff_dinode(ip, page);
 			if (error == 0)
 				goto prepare_write;
 		} else if (!PageUptodate(page))