Switch to using gs101 instead of valhall for GPU UMD

Preparing for deviation of gs101 UMD from other devices.

This change has no on-device functional behavior impact. The change only picks
the UMD source from a new location, the actual driver should be the same
as earlier.

Flag: EXEMPT for switching where the UMD source is picked up.
Bug: 360830887
Test: Local build
Change-Id: I033c7553c94bed67fa6b6fc2d407b48e8b6d1a3e
1 file changed