My Samsung Galaxy S6 is bricked I recently bricked my Samsung Galaxy S6 SM-S906l while trying to flash TWRP recovery.

Apparently, it was an unsupported recovery and I need to reflash the original recover with Odin, but it says it needs the PIT file.

How do you obtain the PIT file?
The SM-S906L is the same device as the SM-G920V [source]. You should be able to use the PIT for the SM-G920V. You can get the PIT here. 

I also found it here (and it is labeled as the SM-S906L, but has the same file name as the one that is specified for the SM-G920V).