LU-8003 llite: remove obsolete code and comments

LU-8003 llite: remove obsolete code and comments

Remove obsolete comments about the behavior of ll_ddelete() and the
removed function ll_d_iput(). Remove '#if 0'-ed out code from
ll_ddelete().

Test-Parameters: trivial

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Change-Id: Id2f2eed8e96ee07fdcd4ec14c4e82ed463752562
Reviewed-on: http://review.whamcloud.com/19881
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andrew Perepechko <andrew.perepechko@seagate.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>