Revert "freedreno: Account for multi-draw in num_draws"

autotune already divides draw-cost by # of draws, but only increments the draw-cost once per multi-draw. We could either also account for draw-cost by multiply by # of draws for treat multi-draw as a single draw. The latter saves an integer multiply per draw.

Fixes a performance regression triggered by transition from GMEM to sysmem rendering.

This reverts commit 6bfee9e6.