LU-4423 ptlrpc: use 64-bit times in ptlrpc_enc_page_pool

LU-4423 ptlrpc: use 64-bit times in ptlrpc_enc_page_pool

ptlrpc_enc_page_pool computes time deltas using 'long' values from
get_seconds(). This is probably safe beyond y2038, but it's better
to go use monotonic times and 64-bit here for consistency.

Linux-commit: 80018a9edbc3180ae31a7197f9dacab975a7f5e2

Change-Id: I15511b04d8b4f7353ce109d8d9bb7887f551d880
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/24708
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>