spirv: remove const qualifier on vtn_emit_kernel_entry_point_wrapper()

To silence a compiler warning/error about a const/non-const mismatch
when calling nir_call_instr_create (expects non-const).

Signed-off-by: Tapani Pälli <tapani.palli@intel.com>
21 jobs for !472 with remove-const-spirv in 43 minutes and 41 seconds (queued for 3 seconds)
latest detached
Status Job ID Name Coverage
  Containers Build
passed #179852
ubuntu

00:01:27

 
  Build+Test
passed #179866
make-gallium-drivers-other

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passed #179865
make-gallium-drivers-radeonsi

00:13:55

passed #179864
make-gallium-drivers-swr

00:14:27

passed #179867
make-gallium-st-clover-llvm

00:11:19

passed #179868
make-gallium-st-clover-llvm-39

00:08:31

passed #179869
make-gallium-st-other

00:08:55

passed #179863
make-loader-classic-dri

00:12:30

passed #179862
make-vulkan

00:07:45

passed #179859
meson-gallium-clover-llvm

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passed #179860
meson-gallium-clover-llvm39

00:02:36

passed #179858
meson-gallium-drivers-other

00:09:48

passed #179857
meson-gallium-radeonsi

00:04:41

passed #179861
meson-gallium-st-other

00:04:30

passed #179856
meson-gallium-swr

00:11:20

passed #179855
meson-glvnd

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passed #179854
meson-loader-classic-dri

00:07:04

passed #179853
meson-vulkan

00:04:26

passed #179871
scons-llvm

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passed #179870
scons-nollvm

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passed #179872
scons-swr

00:09:37