Fix output stream operator for Pipeline version.

include/ck/tensor_operation/gpu/grid/gridwise_gemm_pipeline_selector.hpp

@@ -56,7 +56,7 @@ inline std::string getPipelineVersionString(const PipelineVersion& pv)
 
 } // namespace ck
 
-std::ostream& operator<<(std::ostream& os, const ck::PipelineVersion pv)
+inline std::ostream& operator<<(std::ostream& os, const ck::PipelineVersion pv)
 {
     os << ck::getPipelineVersionString(pv);
     return os;