pan/midgard: Fix writeout combining

pan/midgard: Fix writeout combining

shader-db regression in the scheduler.

Fixes: dff4986b1aa ("pan/midgard: Emit store_output branch just-in-time")
total bundles in shared programs: 2055 -> 2019 (-1.75%)
bundles in affected programs: 1055 -> 1019 (-3.41%)
helped: 36
HURT: 0
helped stats (abs) min: 1 max: 1 x̄: 1.00 x̃: 1
helped stats (rel) min: 0.35% max: 20.00% x̄: 6.71% x̃: 5.16%
95% mean confidence interval for bundles value: -1.00 -1.00
95% mean confidence interval for bundles %-change: -8.45% -4.97%
Bundles are helped.

total quadwords in shared programs: 3444 -> 3408 (-1.05%)
quadwords in affected programs: 1897 -> 1861 (-1.90%)
helped: 36
HURT: 0
helped stats (abs) min: 1 max: 1 x̄: 1.00 x̃: 1
helped stats (rel) min: 0.19% max: 14.29% x̄: 3.97% x̃: 2.99%
95% mean confidence interval for quadwords value: -1.00 -1.00
95% mean confidence interval for quadwords %-change: -5.08% -2.86%
Quadwords are helped.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>