reiserfs: cleanup, rename key and item accessors to more friendly names

This patch does a quick search and replace:
B_N_PITEM_HEAD() -> item_head()
B_N_PDELIM_KEY() -> internal_key()
B_N_PKEY() -> leaf_key()
B_N_PITEM() -> item_body()

And the item_head version:
B_I_PITEM() -> ih_item_body()
I_ENTRY_COUNT() -> ih_entry_count()

And the treepath variants:
get_ih() -> tp_item_head()
PATH_PITEM_HEAD() -> tp_item_head()
get_item() -> tp_item_body()

... which makes the code much easier on the eyes.

I've also removed a few unused macros.

Checkpatch will complain about the 80 character limit for do_balan.c.
I've addressed that in a later patchset to split up balance_leaf().

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Jan Kara <jack@suse.cz>
diff --git a/fs/reiserfs/super.c b/fs/reiserfs/super.c
index 16927b8..c02b6b0 100644
--- a/fs/reiserfs/super.c
+++ b/fs/reiserfs/super.c
@@ -258,7 +258,7 @@
 			break;
 		}
 		item_pos--;
-		ih = B_N_PITEM_HEAD(bh, item_pos);
+		ih = item_head(bh, item_pos);
 
 		if (le32_to_cpu(ih->ih_key.k_dir_id) != MAX_KEY_OBJECTID)
 			/* there are no "save" links anymore */
@@ -271,7 +271,7 @@
 			truncate = 0;
 
 		/* reiserfs_iget needs k_dirid and k_objectid only */
-		item = B_I_PITEM(bh, ih);
+		item = ih_item_body(bh, ih);
 		obj_key.on_disk_key.k_dir_id = le32_to_cpu(*(__le32 *) item);
 		obj_key.on_disk_key.k_objectid =
 		    le32_to_cpu(ih->ih_key.k_objectid);