[Intel-gfx] [CI 2/5] drm/i915: Remove obsolete ringbuffer emission for gen8+

Since removing the module parameter to force selection of ringbuffer emission for gen8, the code is defunct. Remove it. To put the difference into perspective, a couple of microbenchmarks (bdw i7-5557u, 20170324): ring execlists exec continuous

[Intel-gfx] [CI 2/5] drm/i915: Remove obsolete ringbuffer emission for gen8+

Since removing the module parameter to force selection of ringbuffer emission for gen8, the code is defunct. Remove it. To put the difference into perspective, a couple of microbenchmarks (bdw i7-5557u, 20170324): ring execlists exec continuous