xfs: Remove two dead transaction log reservaion macros

Upstream commit 5b292ae3a951a58e32119d73c7ac8f5bec7395a3
	xfs: make use of xfs_calc_buf_res() in xfs_trans.c

Beginning from above commit, neither XFS_ALLOCFREE_LOG_RES() nor
XFS_DIROP_LOG_RES() is used by those routines for calculating
transaction space reservations, so it's safe to remove them now.

Also, with a slightly update for the relevant comments to reflect
the ideas of why those log count numbers should be.

Signed-off-by: Jie Liu <jeff.liu@oracle.com>
Reviewed-by: Ben Myers <bpm@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

fs/xfs/xfs_trans.h

@@ -210,23 +210,18 @@ struct xfs_log_item_desc {
 /*
  * Per-extent log reservation for the allocation btree changes
  * involved in freeing or allocating an extent.
- * 2 trees * (2 blocks/level * max depth - 1) * block size
+ * 2 trees * (2 blocks/level * max depth - 1)
  */
-#define	XFS_ALLOCFREE_LOG_RES(mp,nx) \
-	((nx) * (2 * XFS_FSB_TO_B((mp), 2 * XFS_AG_MAXLEVELS(mp) - 1)))
 #define	XFS_ALLOCFREE_LOG_COUNT(mp,nx) \
 	((nx) * (2 * (2 * XFS_AG_MAXLEVELS(mp) - 1)))
 
 /*
  * Per-directory log reservation for any directory change.
- * dir blocks: (1 btree block per level + data block + free block) * dblock size
- * bmap btree: (levels + 2) * max depth * block size
+ * dir blocks: (1 btree block per level + data block + free block)
+ * bmap btree: (levels + 2) * max depth
  * v2 directory blocks can be fragmented below the dirblksize down to the fsb
  * size, so account for that in the DAENTER macros.
  */
-#define	XFS_DIROP_LOG_RES(mp)	\
-	(XFS_FSB_TO_B(mp, XFS_DAENTER_BLOCKS(mp, XFS_DATA_FORK)) + \
-	 (XFS_FSB_TO_B(mp, XFS_DAENTER_BMAPS(mp, XFS_DATA_FORK) + 1)))
 #define	XFS_DIROP_LOG_COUNT(mp)	\
 	(XFS_DAENTER_BLOCKS(mp, XFS_DATA_FORK) + \
 	 XFS_DAENTER_BMAPS(mp, XFS_DATA_FORK) + 1)