jfs: remove DIRENTSIZ

After fat gets fixed the unused DIRENTSIZ macro was the last user of
struct dirent we should get rid of since the kernel and userspace
versions differed.
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>

fs/jfs/jfs_dtree.h

@@ -243,9 +243,6 @@ typedef union {
 #define JFS_REMOVE 3
 #define JFS_RENAME 4
 
-#define DIRENTSIZ(namlen) \
-    ( (sizeof(struct dirent) - 2*(JFS_NAME_MAX+1) + 2*((namlen)+1) + 3) &~ 3 )
-
 /*
  * Maximum file offset for directories.
  */