Certain non-standard float types were directly passed through in the
LLVM type converter, resulting in invalid IR or failed assertions:
```
mlir-opt: mlir/lib/Conversion/LLVMCommon/TypeConverter.cpp:638: FailureOr<Type> mlir::LLVMTypeConverter::convertVectorType(VectorType) const: Assertion `LLVM::isCompatibleVectorType(vectorType) && "expected vector type compatible with the LLVM dialect"' failed.
```
The LLVM type converter should not define invalid type conversion rules
for such types. If there is no type conversion rule, conversion patterns
will not apply to ops with such operand types.