What will happen to TLV1117 (5V / 3.3V) from reverse voltage?
Is it necessary to put a diode on the 3.3V output?


No. The regulator output will draw a few mA when voltage is back-fed into it from the USBASP, but this won't harm it. 

However it could damaged if there is a large amount of uncharged input filter capacitance. To prevent this you should disconnect the power supply unit when programming, and only have a small capacitor (eg. 10uF) close to the regulator input. 

A diode (preferably Schottky type for low voltage drop) between the power supply and regulator (before the 10uF capacitor) will also help to isolate it from the power supply capacitance, as well as protecting it from reverse voltage.