LU-4460 mount: fix lmd_parse() to handle comma-separated NIDs

LU-4460 mount: fix lmd_parse() to handle comma-separated NIDs

This patch reverts commit 3917e62018878dfffac59ceed70f20b0419945d3,
which cannot handle the upgrade situation that old mountdata already
contains comma-separated NIDs. The correct way to fix the original
issue is to parse comma-separated NIDs in lmd_parse().

The patch also updates disk2_4-ldiskfs.tar.bz2 to make the mountdata
of ost contain comma-separated NIDs so as to verify the patch under
upgrade situation.

Test-Parameters: alwaysuploadlogs \
envdefinitions=SLOW=yes,ENABLE_QUOTA=yes testlist=conf-sanity

Signed-off-by: Jian Yu <jian.yu@intel.com>
Change-Id: If179618c9c89dc2168f748aeba59384ea31197ff
Reviewed-on: http://review.whamcloud.com/8918
Tested-by: Maloo <hpdd-maloo@intel.com>
Tested-by: Jenkins
Reviewed-by: Niu Yawei <yawei.niu@intel.com>
Reviewed-by: Bobi Jam <bobijam@gmail.com>
Reviewed-by: Sebastien Buisson <sebastien.buisson@bull.net>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>