wsi: query the ICD's max dimensions instead of hard-coding them

anv and radv both happened to already return 2^14 for these, but
querying the ICD is safer and will help if vdreno (or whatever it's
called) doesn't have the same max.

Signed-off-by: Eric Engestrom <eric.engestrom@intel.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
24 jobs for misc/wsi-imageextent in 42 minutes and 28 seconds (queued for 46 minutes and 24 seconds)
Status Job ID Name Coverage
  Build+Test
passed #105271
build:make-gallium-drivers-other

00:10:40

passed #105270
build:make-gallium-drivers-radeonsi

00:07:48

passed #105269
build:make-gallium-drivers-swr

00:12:43

passed #105272
build:make-gallium-st-clover-llvm-39

00:07:43

passed #105273
build:make-gallium-st-clover-llvm-4

00:09:33

passed #105274
build:make-gallium-st-clover-llvm-5

00:09:13

passed #105275
build:make-gallium-st-clover-llvm-6

00:08:42

passed #105276
build:make-gallium-st-clover-llvm-7

00:09:10

passed #105277
build:make-gallium-st-other

00:09:31

passed #105268
build:make-loader-classic-dri

00:11:16

passed #105267
build:make-vulkan

00:06:04

passed #105263
build:meson-gallium-clover-llvm5

00:02:54

passed #105264
build:meson-gallium-clover-llvm6

00:02:47

passed #105265
build:meson-gallium-clover-llvm7

00:02:22

passed #105262
build:meson-gallium-drivers-other

00:02:47

passed #105261
build:meson-gallium-radeonsi

00:01:54

passed #105266
build:meson-gallium-st-other

00:02:11

passed #105260
build:meson-gallium-swr

00:03:01

passed #105259
build:meson-glvnd

00:02:24

passed #105258
build:meson-loader-classic-dri

00:02:27

passed #105257
build:meson-vulkan

00:01:08

passed #105279
build:scons-llvm

00:04:39

passed #105278
build:scons-nollvm

00:04:17

passed #105280
build:scons-swr

00:07:40