Instead of emptying the caches to avoid a race with the PFIFO puller,
go straight ahead and try to recover from it when it happens. Also,
kill pfifo->cache_flush and tile->lock, we don't need them anymore.
Signed-off-by: NFrancisco Jerez <currojerez@riseup.net>
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>