staging/lustre/mdc: Zero atime in close RPC

While atime on close is supposed to only increase, there's
a bug in some older server versions where atime from a client
is taken no matter the value that allows a stale client atime
to overwrite a correct value.

Update atime in close rpc to 0 to help such servers out.

Signed-off-by: Niu Yawei <yawei.niu@intel.com>
Reviewed-on: http://review.whamcloud.com/19932
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-8041


Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>