You will need to connect VCCA to 2.5V even if you don't use the PLL. From the datasheet - "(1) You must power up VCCA even if the PLL is not used." You will not detect the FPGA without it.
If you don't have a 2.5V supply you will get away with a potential divider (two resistors) from a higher voltage rail e.g. 3.3V. It's not recommended but if you're not using the PLL it should get you up and running.
I recommend adding a separate 2.5V regulator (@$0.35) for VCCA if you re-spin the board.