i965: Enumerate Observability Architecture counters on Gen5+.

i965: Enumerate Observability Architecture counters on Gen5+.

In addition to listing the counter names, we include several "remap"
tables.  Confusingly, counters are documented with names like "A23",
are written to some buffer offset other than 23, and exposed by core
Mesa under a counter ID that is different still.

The first is inevitable; MI_REPORT_PERF_COUNT writes certain counters to
fixed locations in the buffer.  The latter could be avoided, but core
Mesa uses the "Counters" array index as the ID for a counter.  We could
do remapping there, but it would just complicate the core Mesa code.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Eric Anholt <eric@anholt.net>