mb/google/rex/var/karis: Set VPU disable as default

BUG=b:299374763
TEST=emerge-rex coreboot

Change-Id: I40fc768522e8679337c3b9f5497278e9f4639c3e
Signed-off-by: Tyler Wang <tyler.wang@quanta.corp-partner.google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/77888
Reviewed-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>
Reviewed-by: Kapil Porwal <kapilporwal@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/rex/variants/karis/overridetree.cb

@@ -250,7 +250,6 @@ chip soc/intel/meteorlake
 		end # PCIE10 SSD card
 		device ref tbt_pcie_rp0 on end
 		device ref tbt_pcie_rp2 on end
-		device ref vpu on end
 		device ref tcss_xhci on
 			chip drivers/usb/acpi
 				device ref tcss_root_hub on