LU-6245 libcfs: remove cfs_fs_time handling

LU-6245 libcfs: remove cfs_fs_time handling

Only the mdd layer uses cfs_fs_time handling. We can
easily convert it to the standard linux kernel time
keeping api in the latest kernels. Besides this change
the handling of time in 64 bits to avoid the 2038
limit is introduced.

Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Change-Id: I0bac2020d078c2d91347f5a3a68e99d25ba97575
Reviewed-on: http://review.whamcloud.com/22857
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Frank Zago <fzago@cray.com>
Reviewed-by: Doug Oucharek <doug.s.oucharek@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>