LU-4423 ptlrpc: use 64-bit times for ptlrpc_sec

LU-4423 ptlrpc: use 64-bit times for ptlrpc_sec

Here we use an unsigned long to store the timeout for gc,
which is probably safe until 2106, but this patch converts it
to use ktime_get_real_seconds() and time64_t for consistency.

Linux-commit: 8cc980713ec9e6847896891c54562ad815c33424

Change-Id: I9c66ac818239debe676b78fbee5764cd5b69028c
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/24710
Tested-by: Jenkins
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>