sconfig: rename pci_domain -> domain

The name pci_domain was a bit misleading, since the construct is only
PCI specific in a particular (northbridge/cpu) implementation, but not
by concept. As implementations and hardware change, be more generic
about our naming. This will allow us to support non-PCI systems without
adding new keywords.

Change-Id: Ide885a1d5e15d37560c79b936a39252150560e85
Signed-off-by: Stefan Reinauer <reinauer@google.com>
Reviewed-on: http://review.coreboot.org/2376
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

src/mainboard/intel/emeraldlake2/devicetree.cb

@@ -27,7 +27,7 @@ chip northbridge/intel/sandybridge
 		end
 	end
 
-	device pci_domain 0 on
+	device domain 0 on
 		device pci 00.0 on end # host bridge
 		device pci 02.0 on end # vga controller