nb/intel/nehalem: Disable PEG and IGD based on devicetree

Tested on Thinkpad X201: PEG device hidden.

Change-Id: Ib378458a55e18cc02fc49b3e6d6939d31dd4aa65
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/35744
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/packardbell/ms2290/devicetree.cb

@@ -48,6 +48,7 @@ chip northbridge/intel/nehalem
 		device pci 00.0 on # Host bridge
 			subsystemid 0x1025 0x0379
 		end
+		device pci 01.0 off end # PEG
 		device pci 02.0 on # VGA controller
 			subsystemid 0x1025 0x0379
 		end