Yes, that was my intent as well but I decided to control it on the software site as my led power supply also powers my pi
Be aware that most tv havent a current regulator in the usb port and could blow up. I hope you double checked it could deliver enough current for your pi.
So for you its easy to connect a relays or fet on one of the gpios and configure it in the boot setup like init.d as described here http://raspberrypi.stackexchan…etting-gpio-value-on-boot