nir: const `nir_call_instr::callee`
Fixes: c95afe56 "nir/spirv: handle kernel function parameters"
/cc @karolherbst @jekstrand @tpalli
See https://gitlab.freedesktop.org/eric/mesa/-/jobs/180159 and https://travis-ci.org/mesa3d/mesa/jobs/508218259
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Fixes: c95afe56 "nir/spirv: handle kernel function parameters"
/cc @karolherbst @jekstrand @tpalli
See https://gitlab.freedesktop.org/eric/mesa/-/jobs/180159 and https://travis-ci.org/mesa3d/mesa/jobs/508218259