hwdocs/pcounter: Tested on NV98
hwdocs/pcounter: Move vertex_attribute_count to the VS signals section
hwdocs/pcounter: Add rop_samples_in_count, a new signal which is not documented in the NVPerfSDK manual
hwdocs/pcounter: Update rasterize_pixels_killed_zcull_count from GDebugger's documentation
hwdocs/pcounter: Add description of rasterizer_tiles_in_count and rasterizer_pixels_out_count