Bug 1250: fix pow() for AutoDiffScalar with custom nested scalar type.
Bug 1250: fix pow() for AutoDiffScalar with custom nested scalar type.

ROCmSoftwarePlatform/hipeigen,ROCmSoftwarePlatform/hipeigen,pasuka/eigen,pasuka/eigen,pasuka/eigen,ritsu1228/eigen,ritsu1228/eigen,ritsu1228/eigen,ROCmSoftwarePlatform/hipeigen,ritsu1228/eigen,ritsu1228/eigen,ROCmSoftwarePlatform/hipeigen,pasuka/eigen,pasuka/eigen