LU-445 lnet: Make previous change backwards compatible

LU-445 lnet: Make previous change backwards compatible

With the previous patch as is, a 2.3 system running against
a 2.2 or 2.1 system will have an invalid timestamp for doing
bandwidth calculations.

This patch checks the value of the timestamp field to
determine if it is a valid value (>= 2.3) or is too small
to be a timestamp (< 2.3). If it is a valid timestamp, it
will be used. If not, the local timestamp will be used.

Signed-off-by: Doug Oucharek <doug@whamcloud.com>
Change-Id: If655144de72d3e46ab32acfcfc35ed79f58d00b2
Reviewed-on: http://review.whamcloud.com/3192
Tested-by: Hudson
Reviewed-by: Liang Zhen <liang@whamcloud.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>