I'm not aware of any temperature sensors which simply have a parallel interface output, but I could be wrong.
If the PLD has a built in ADC, you could use that with an analogue temperature sensor. Alternatively you could even use an analogue temperature sensor and parallel output ADC.
As another option you could use a microcontroller to talk to the temp sensor over I2C/SPI and present the data as a parallel bus to the PLD.
To be honest though, writing a state machine to read the temperature sensor directly using I2C/SPI inside the PLD probably isn't that as hard as you think, and is likely simpler than adding lots of extra circuitry. Examples of SPI/I2C masters in Verilog and VHDL are readily available on the internet.