Overclock Pi in Ubuntu on-demand

[veerendra2]

• https://www.raspberrypi.com/documentation/computers/config_txt.html
• https://www.reddit.com/r/raspberry_pi/comments/139flkn/raspberry_pi_4b_overclocked_to_2390_ghz/
• https://friendsoflittleyus.nl/overclocking-raspberry-pi4-on-ubuntu-21-10/
• https://beebom.com/how-overclock-raspberry-pi-4/

[veerendra2]