rx: Avoid new server calls for big-seq DATA pkts

rx: Avoid new server calls for big-seq DATA pkts

We currently never open our receive window to more than 32 packets. If
we received a DATA packet for an unrecognized call with a seq of 33 or
more, the packet is almost certainly from a previously-running call
that we were restarted during.

As described in commit 7b204946 (rx: Avoid lastReceiveTime update for
invalid ACKs) and commit "rx: Avoid new server calls for non-DATA
packets", clients can get confused when we respond to calls in these
situations, so drop the packets instead.

Change-Id: I5b3a699bf245375e92ac97a24ad3638cbb3b8f3c
Reviewed-on: https://gerrit.openafs.org/13876
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>