Add flash support for VCU128

VCU128 does not have secondary flash.

src/xilinx.cpp

@@ -167,6 +167,9 @@ Xilinx::Xilinx(Jtag *jtag, const std::string &filename,
 		_secondary_file_extension = secondary_filename.substr(
 			secondary_filename.find_last_of(".") + 1);
 		_mode = Device::SPI_MODE;
+		if (_device_package != "xcvu9p-flga2104") {
+			throw std::runtime_error("Error: secondary flash unavailable");
+		}
 	}
 
 	uint32_t idcode = _jtag->get_target_device_id();