mb/google/rex: Enable VPU device for Rex/Ovis baseboard

This patch enables the Versatile Processing Unit (VPU) by default for
Rex/Ovis baseboard. VPU is a dedicated AI engine that is included in
the 14th generation "Meteor Lake" Core processors.

The VPU is designed to efficiently run AI models directly on the
system on chip (SoC). There is no power regression observed while
keeping the VPU default enabled to run AI models natively hence, this
patch enables the VPU by default.

BUG=b:332488817
TEST=Able to see VPU PCI device in lspci (0:11:0) list after booting
google/screebo to OS.

Change-Id: I8b3521c8ec613b002f971eaf9d346927fe8cd656
Signed-off-by: Subrata Banik <subratabanik@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/82422
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Sumeet R Pawnikar <sumeet.r.pawnikar@intel.com>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Jamie Ryu <jamie.m.ryu@intel.com>
Reviewed-by: Dinesh Gehlot <digehlot@google.com>
Reviewed-by: Eric Lai <ericllai@google.com>

src/mainboard/google/rex/variants/baseboard/ovis/devicetree.cb

@@ -86,6 +86,7 @@ chip soc/intel/meteorlake
 	device domain 0 on
 		device ref igpu on end
 		device ref dtt on end
+		device ref vpu on end
 		device ref ioe_shared_sram on end
 		device ref xhci on end
 		device ref pmc_shared_sram on end

src/mainboard/google/rex/variants/baseboard/rex/devicetree.cb

@@ -97,6 +97,7 @@ chip soc/intel/meteorlake
 	device domain 0 on
 		device ref igpu on end
 		device ref dtt on end
+		device ref vpu on end
 		device ref ioe_shared_sram on end
 		device ref xhci on end
 		device ref pmc_shared_sram on end