iris: enable preemption support for gen10

this automatically enables preemption on gen10 where it is disabled by
default but still available
14 jobs for !661 with iris-preempt in 16 minutes and 54 seconds (queued for 4 seconds)
latest detached
Status Job ID Name Coverage
  Containers Build
passed #253572
debian

00:00:22

 
  Build+Test
passed #253574
meson-clang

00:16:31

passed #253580
meson-gallium-clover-llvm

00:05:37

passed #253581
meson-gallium-clover-llvm39

00:05:28

passed #253579
meson-gallium-drivers-other

00:10:41

passed #253578
meson-gallium-radeonsi

00:05:57

passed #253582
meson-gallium-st-other

00:05:32

passed #253573
meson-gallium-swr

00:13:29

passed #253577
meson-glvnd

00:06:08

passed #253576
meson-loader-classic-dri

00:06:33

passed #253575
meson-vulkan

00:04:09

passed #253584
scons-llvm

00:07:04

passed #253583
scons-nollvm

00:04:08

passed #253585
scons-swr

00:06:33