It disables one of the PSP DXE Drivers in the BIOS code. (fTPM)
But there are many many many many more parts to the puzzle. I wouldn’t even begin to say this “Allows disabling PSP” due how much of an Integral Part the Platform Security Processor is.
Likely some of the 3 below and including the highlighted one are involved.
Also take note of AmiAgesaDXE as opposed to AmdAgesaDXE 
Here’s a dump of all ~240 something the Readable DXE Drivers and other registered modules in the average Ryzen BIOS taken from ASRock X370 Gaming K4 version 4.1
(4.1 being the Agesa 1.0.7.2 version that has since been pulled from a lot of Firmware sites.)
Also the as yet 268 unknown GUID’s:
And all this is just from one Volume Image subsection in the firmware file
