Yes, you can use the EPCQ256 configuration device for RSU with Arria® II, Stratix® IV, Cyclone® IV and older devices but you have to make sure that the application image start address is within the first 128Mbits of the EPCQ device to allow successful configuration to the application image.
If you are using your controller to program EPCQ device in 4-byte addressing mode, ensure the EPCQ device is set to 3 byte addressing mode prior to configuration to allow successful configuration.