Fix OpAsmTargetINTEL operand

[jdnk]

The OpAsmTargetINTEL instruction had an extra Result Type operand which is not specified in the extension https://github.com/intel/llvm/blob/sycl/sycl/doc/design/spirv-extensions/SPV_INTEL_inline_assembly.asciidoc. This causes errors in tools relying on the headers.

Small example of the failure:

// foo.c
void foo (const float * restrict a, const float * restrict b, float * restrict c) {
    __asm__ ("nop");
}

Compile to .spt via llc:

clang -S -emit-llvm -O3 foo.c -o foo.ll
llc -O3 -mtriple=spirv64-unknown-unknown --spirv-ext=+SPV_INTEL_inline_assembly foo.ll -o foo.spt

The output contains something like %12 = OpAsmTargetINTEL "spirv64-unknown-unknown", without any result type. Then, running spirv-as foo.spt -o foo.spv fails because return type is expected.

Tagging @mmerecki who worked on the extension.

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