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/dir.c b/fs/reiserfs/dir.c
index af67735..1fe5cde 100644
--- a/fs/reiserfs/dir.c
+++ b/fs/reiserfs/dir.c
@@ -110,17 +110,17 @@
 		       item_num, B_NR_ITEMS(bh));
 
 		/* and entry must be not more than number of entries in the item */
-		RFALSE(I_ENTRY_COUNT(ih) < entry_num,
+		RFALSE(ih_entry_count(ih) < entry_num,
 		       "vs-9010: entry number is too big %d (%d)",
-		       entry_num, I_ENTRY_COUNT(ih));
+		       entry_num, ih_entry_count(ih));
 
 		if (search_res == POSITION_FOUND
-		    || entry_num < I_ENTRY_COUNT(ih)) {
+		    || entry_num < ih_entry_count(ih)) {
 			/* go through all entries in the directory item beginning from the entry, that has been found */
 			struct reiserfs_de_head *deh =
 			    B_I_DEH(bh, ih) + entry_num;
 
-			for (; entry_num < I_ENTRY_COUNT(ih);
+			for (; entry_num < ih_entry_count(ih);
 			     entry_num++, deh++) {
 				int d_reclen;
 				char *d_name;