[SLPVectorizer] Remove default OperandValueKind arguments from getArithmeticInstrCost calls (NFC)

The getArithmeticInstrCost calls for shuffle vectors entry costs specify TargetTransformInfo::OperandValueKind arguments, but are just using the method's default values. This seems to be a copy + paste issue and doesn't affect the costs in anyway. The TargetTransformInfo::OperandValueProperties default arguments are already not being used.

Noticed while working on D47985.

Differential Revision: https://reviews.llvm.org/D48008

llvm-svn: 335045