spirv: fix using OpSampledImage with OpUndef instead of OpType{Image,Sampler}

spirv: fix using OpSampledImage with OpUndef instead of OpType{Image,Sampler}

This seems valid per the SPIR-V spec to use OpSampledImage with
OpUndef instead of OpTypeImage or OpTypeSampler. When the image
operand is undefined, SPIRV->NIR emits an undef instruction that
can be removed later by the compiler.

This fixes shader compilation crashes with Red Dead Redemption II.

Cc: mesa-stable@lists.freedesktop.org>
Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5230>