Added missing EIGEN_DEVICE_FUNC qualifiers to several nullary op methods.
Added missing EIGEN_DEVICE_FUNC qualifiers to several nullary op methods.

ritsu1228/eigen,ritsu1228/eigen,ritsu1228/eigen,pasuka/eigen,pasuka/eigen,pasuka/eigen,ritsu1228/eigen,ritsu1228/eigen,pasuka/eigen,pasuka/eigen