LU-4423 osc: use 64-bit timestamps in debugfs output

LU-4423 osc: use 64-bit timestamps in debugfs output

Some lustre debugfs files contain the current time. Make sure
we use a format here that does not overflow in 2038.

Linux-commit: 86655400c6e74751a73be82ea40d5ae6979c3225

Change-Id: I8a79e60bd15ce7c162b30025ca3b572fec2ee58f
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-on: https://review.whamcloud.com/25407
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>