LU-13344 ptlrpc: change request timeouts to s32

LU-13344 ptlrpc: change request timeouts to s32

In the latest kernels time_t has been removed since time_t has
been a 64 bit value just like time64_t so no need for it anymore.
This means all kernel time keeping are all 64 bits but Lustre
sends 32 bit values, in seconds, for its timeout between nodes.
To keep backwards compatibility as well as distinguish timeouts
from timestamps change the Lustre fields representing timeouts
to a new typedef timeout_t which is a s32. The reason for picking
a signed number is that it makes it easier to detect if an
incorrect timeout was calculated. In the past negative timeouts
have happened which would look like an enormous timeout if its
treated as an unsigned number.

Change-Id: I7491bbac65023c544e8f4a0488b1d07315a739e5
Signed-off-by: James Simmons <jsimmons@infradead.org>
Reviewed-on: https://review.whamcloud.com/37933
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Shaun Tancheff <shaun.tancheff@hpe.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Neil Brown <neilb@suse.de>
Reviewed-by: Oleg Drokin <green@whamcloud.com>