[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_vm.c b/fs/gfs2/ops_vm.c
index 08709f1..910722d 100644
--- a/fs/gfs2/ops_vm.c
+++ b/fs/gfs2/ops_vm.c
@@ -104,7 +104,7 @@
 		goto out_ipres;
 
 	if (gfs2_is_stuffed(ip)) {
-		error = gfs2_unstuff_dinode(ip, gfs2_unstuffer_page, NULL);
+		error = gfs2_unstuff_dinode(ip, NULL);
 		if (error)
 			goto out_trans;
 	}