LU-4423 obd: backport of lu_object changes upstream

LU-4423 obd: backport of lu_object changes upstream

fold lu_object_new() into lu_object_find_at()

lu_object_new() duplicates a lot of code that is in
lu_object_find_at().
There is no real need for a separate function, it is simpler just
to skip the bits of lu_object_find_at() that we don't
want in the LOC_F_NEW case.

Linux-commit: 775c4dc274343e5e2959fa1171baf2fc01028840

discard extra lru count.

lu_object maintains 2 lru counts.
One is a per-bucket lsb_lru_len.
The other is the per-cpu ls_lru_len_counter.

The only times the per-bucket counters are use are:
 - a debug message when an object is added
 - in lu_site_stats_get when all the counters are combined.

The debug message is not essential, and the per-cpu counter
can be used to get the combined total.

So discard the per-bucket lsb_lru_len.

Linux-commit: e167b370360f8887cf21a2a82f83e7118a2aeb11

make struct lu_site_bkt_data private

This data structure only needs to be public so that
various modules can access a wait queue to wait for object
destruction.
If we provide a function to get the wait queue, rather than the
whole bucket, the structure can be made private.

Linux-commit: bc5e7fb40d36edb95ce8f661596811bec3f7d5cf

Change-Id: I26203f331a0c73ae4e23878eb10b15d9fcf546c5
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-on: https://review.whamcloud.com/32325
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>