[GUP] Hard code the name of the whitelist file.

Allowing customized whitelist filename could result in inconsistency and
fragmentations in toolings.

BUG: 120870520
Test: Build, flash and boot
Change-Id: Ibe9337b358b6a67600048f1661d73574d7bea607
Merged-In: Ibe9337b358b6a67600048f1661d73574d7bea607