LU-1607 tests: enable multiple CPU Partitions

LU-1607 tests: enable multiple CPU Partitions

CPU partitions number of libcfs is explicitly set to 1 which means
most SMP features are disabled by default, the reason we didn't
enable it so far is because enabling it will break some tests
because change of /proc interfaces or modparameters.

This patch covered a few things:
- use 0 as default value of cpu_npartitions
  libcfs will estimate CPU partition number based on cores
  or NUMA nodes
- a small fix for LNet
  ni_last_alive should use second instead of jiffies as time stamp
- always enable multiple CPU partitions in test-framework
- fix test_215 for sanity
- fix test_52 for conf-sanity

Signed-off-by: Liang Zhen <liang@whamcloud.com>
Change-Id: Ib1a296e254a7b2e91e8d77337a9cd9ac877321e3
Reviewed-on: http://review.whamcloud.com/3288
Tested-by: Hudson
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Bobi Jam <bobijam@whamcloud.com>
Reviewed-by: wangdi <di.wang@whamcloud.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>