ppsi: use new master, with some timestamp fixes

The bug we were facing was in wr-nic.ko (previous commit fixes it),
but we made a few changes to the better in ppsi handing of timestamps
(wrs-socket.c) while looking for that problem. So this picks those
4 commits of ppsi:
wrs-socket: decrease the timeout when waiting for a timestamp
wrs-socket: simplify the code retrieving timestamps
unix and wrs socket: open in non-blocking mode and report write errors
wrs-socket: use POLLERR for timestamps
Signed-off-by: Alessandro Rubini <rubini@gnudd.com>