RD llvm: fix getting operand in undefined call
RD llvm: fix getting operand in undefined call

we need to use the new getOperand() method

Signed-off-by: Marek Chalupa <a05df156a69ad59faa9af9b666ef78009594c145@gmail.com>

mchalupa/dg,mchalupa/dg,mchalupa/dg,mchalupa/dg