Add performance counters for gfx70x. The reference is the gfx7 register spec.
The register being looked at is SQ_PERFCOUNTER0_SELECT.
Change-Id: I344bfb7452f6148f4dc268163d12c553c6be8424
Few more counters are now available in GFX8 register specs. So adding
them. Also for gfx700 and gfx801 report correct number of SQ perf counter slots
Change-Id: I9e6b4b10238230aabeccbfaa5e491a28b5e54f2d