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/item_ops.c b/fs/reiserfs/item_ops.c
index ee382ef..c9f1365 100644
--- a/fs/reiserfs/item_ops.c
+++ b/fs/reiserfs/item_ops.c
@@ -396,7 +396,7 @@
 
 	deh = (struct reiserfs_de_head *)item;
 
-	for (i = 0; i < I_ENTRY_COUNT(ih); i++, deh++) {
+	for (i = 0; i < ih_entry_count(ih); i++, deh++) {
 		namelen =
 		    (i ? (deh_location(deh - 1)) : ih_item_len(ih)) -
 		    deh_location(deh);
@@ -430,7 +430,7 @@
 
 	// FIXME: type something here!
 	deh = (struct reiserfs_de_head *)item;
-	for (i = 0; i < I_ENTRY_COUNT(ih); i++, deh++) {
+	for (i = 0; i < ih_entry_count(ih); i++, deh++) {
 		;
 	}
 }