[LV] Fix crash when vectorizing function calls with linear args. (#76274)

llvm/lib/IR/Type.cpp:694:
    Assertion `isValidElementType(ElementType) && "Element type of a
    VectorType must be an integer, floating point, or pointer type."'
    failed.
Stack dump:
    llvm::FixedVectorType::get(llvm::Type*, unsigned int)
    llvm::VPWidenCallRecipe::execute(llvm::VPTransformState&)
    llvm::VPBasicBlock::execute(llvm::VPTransformState*)
    llvm::VPRegionBlock::execute(llvm::VPTransformState*)
    llvm::VPlan::execute(llvm::VPTransformState*)
    ...

Happens with function calls of void return type.