[XFS] merge xfs_imap into xfs_dilocate

xfs_imap is the only caller of xfs_dilocate and doesn't add any significant
value.  Merge the two functions and document the various cases we have for
inode cluster lookup in the new xfs_imap.

Also remove the unused im_agblkno and im_ioffset fields from struct xfs_imap
while we're at it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Niv Sardi <xaiki@sgi.com>
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index db1f688..0a9ad1c 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -157,7 +157,7 @@
 #define	XFS_IFEXTIREC	0x08	/* Indirection array of extent blocks */
 
 /*
- * Flags for xfs_inotobp, xfs_imap() and xfs_dilocate().
+ * Flags for xfs_inotobp and xfs_imap().
  */
 #define XFS_IMAP_BULKSTAT	0x1