LU-2888 fid: still Use oi_id/oi_seq for log/lov object.

Since llog are only used locally on MDS right now, so we will use
oi_id/oi_seq to identfy the log, instead of trying to convert it to
FID, to avoid confusion in ostid_to_fid/fid_to_ostid.

Since pre-2.4 use {oi_id,oi_seq} for FIDs on MDT, which make
it difficult to tell whether it is ostid or FID by only checking
oi_seq, so this patch will separate lmm_oi/FID conversion from
ostid_to_fid.

Signed-off-by: wang di <di.wang@intel.com>
Change-Id: Ie17b11a8a07ed3a44e41d5e88529541cbd33dd2f
Reviewed-on: http://review.whamcloud.com/6044
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
New tag 2.3.64

Change-Id: Ia40c179b6570f9f97c467498257800c2011d3c57