mb/google/rex/variants/ovis: Add basic DTT

Add default Intel DPTF.

BUG=b:274421383
TEST=util/abuild/abuild -p none -t google/rex -x -a -b ovis

Change-Id: Ib023f6d6d184f6935a6a454250755502a46b707f
Signed-off-by: Jakub Czapiga <jacz@semihalf.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/75580
Reviewed-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Subrata Banik <subratabanik@google.com>

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

@@ -42,6 +42,11 @@ chip soc/intel/meteorlake
 	}"
 
 	device domain 0 on
+		device ref dtt on
+			chip drivers/intel/dptf
+				device generic 0 alias dptf_policy on end
+			end
+		end
 		device ref pcie_rp11 on
 			# Enable SSD Card PCIE 11 using clk 7
 			register "pcie_rp[PCH_RP(11)]" = "{