xfs_repair: remove trace-only 'n' member from da_level_state

xfs_repair: remove trace-only 'n' member from da_level_state

The da_level_state structure contains an 'n' member
when XR_DIR_TRACE is enabled, which is a) write only, and
b) set by a macro which doesn't exist (XFS_BUF_TO_DA_INTNODE)

Removing this structure member fixes compilation with
XR_DIR_TRACE enabled, and also makes da_level_state identical
to dir2_level_state, so the two can be combined later.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>