i965: Add more Haswell OA metrics sets

i965: Add more Haswell OA metrics sets

This extends the brw_oa_hsw.xml to expose these additional queries:

- Compute Metrics Basic Gen7.5
- Compute Metrics Extended Gen7.5
- Memory Reads Distribution Gen7.5
- Memory Writes Distribution Gen7.5
- Metric set Sampler Balance

Signed-off-by: Robert Bragg <robert@sixbynine.org>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Acked-by: Kenneth Graunke <kenneth@whitecape.org>