mapbench: Revert pipeline width code
mapbench: Revert pipeline width code

We never ran with a pipeline width other than 1, and the more complex
communication required to manage the possibility of a bigger pipeline
increased our L3 misses and actually slowed down the benchmark.

bowlofstew/sv6,bowlofstew/sv6,aclements/sv6,aclements/sv6,aclements/sv6,aclements/sv6,bowlofstew/sv6,bowlofstew/sv6,aclements/sv6,bowlofstew/sv6