soc/intel/skylake: Generate DMAR tables for FSP 1.1 boards

Commit c37b0e3 [soc/intel/skylake: Generate ACPI DMAR table]
only generates DMAR tables for boards using FSP 2.0, which
leaves out Skylake Chromebooks, which use FSP 1.1.

Correct this omission by adding the same functionality for
FSP 1.1 boards.

Test: build/boot on U-series Skylake Chromebook, observe
IOMMU fully functional with intel_iommu=on kernel parameter.

Change-Id: I68837f58aac357fa3f58979fe92d8993fae58640
Signed-off-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-on: https://review.coreboot.org/c/30230
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Rudolph <siro@das-labor.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>

src/soc/intel/skylake/chip.c

@@ -60,6 +60,7 @@ static struct device_operations pci_domain_ops = {
 	.set_resources    = &pci_domain_set_resources,
 	.scan_bus         = &pci_domain_scan_bus,
 #if IS_ENABLED(CONFIG_HAVE_ACPI_TABLES)
+	.write_acpi_tables	= &northbridge_write_acpi_tables,
 	.acpi_name		= &soc_acpi_name,
 #endif
 };