soc/apollolake/acpi: Fill ACPI MCFG table

ACPI MCFG table is required for OS to support Enhanced
Configuration Space Access.Apollolake will only support
1 PCI Segment Group, so all the pci bus number from 0
to 0xff will belong to that group.

Change-Id: I3a680eb9c83290cd531159d7e796382a132cd283
Signed-off-by: Lance Zhao <lijian.zhao@intel.com>
Reviewed-on: https://review.coreboot.org/13375
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/soc/intel/apollolake/acpi.c

@@ -18,6 +18,10 @@
 
 unsigned long acpi_fill_mcfg(unsigned long current)
 {
+	/* PCI Segment Group 0, Start Bus Number 0, End Bus Number is 255 */
+	current += acpi_create_mcfg_mmconfig((void *) current,
+					     CONFIG_MMCONF_BASE_ADDRESS, 0, 0,
+					     255);
 	return current;
 }