mesa/st: remove always-false state

This code is essentially dead now.

Signed-off-by: Erik Faye-Lund <erik.faye-lund@collabora.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
14 jobs for !412 with remove-invalid-oom in 7 minutes and 29 seconds (queued for 2 seconds)
detached
Status Job ID Name Coverage
  Containers Build
passed #267343
debian

00:00:21

 
  Build+Test
passed #267345
meson-clang

00:07:05

passed #267351
meson-gallium-clover-llvm

00:03:35

passed #267352
meson-gallium-clover-llvm39

00:03:11

passed #267350
meson-gallium-drivers-other

00:04:18

passed #267349
meson-gallium-radeonsi

00:03:23

passed #267353
meson-gallium-st-other

00:03:42

passed #267344
meson-gallium-swr

00:05:17

passed #267348
meson-glvnd

00:03:18

passed #267347
meson-loader-classic-dri

00:03:30

passed #267346
meson-vulkan

00:02:46

passed #267355
scons-llvm

00:03:47

passed #267354
scons-nollvm

00:04:41

passed #267356
scons-swr

00:06:11