powerpc/sputrace: Use the generic event tracer

I wrote sputrace before generic tracing infrastrucure was available.
Now that we have the generic event tracer we can convert it over and
remove a lot of code:

  8 files changed, 45 insertions(+), 285 deletions(-)

To use it make sure CONFIG_EVENT_TRACING is enabled and then enable
the spufs trace channel by

  echo 1 > /sys/kernel/debug/tracing/events/spufs/spufs_context/enable

and then read the trace records using e.g.

  cat /sys/kernel/debug/tracing/trace

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>