southbridge/amd/sr5650: Add MCFG ACPI table support

As the southbridge largely controls the PCI[e] configuration space
this patch moves the resource allocation from the northbridge
to the southbridge when the extended configuration space region
is enabled.

Change-Id: I0c4ba74ddcc727cd92b848d5d3240e6f9f392101
Signed-off-by: Timothy Pearson <tpearson@raptorengineeringinc.com>
Reviewed-on: https://review.coreboot.org/12050
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>
Tested-by: Raptor Engineering Automated Test Stand <noreply@raptorengineeringinc.com>

src/southbridge/amd/rs780/rs780.c

@@ -15,6 +15,7 @@
 
 #include <console/console.h>
 #include <arch/io.h>
+#include <arch/acpi.h>
 #include <device/device.h>
 #include <device/pci.h>
 #include <device/pci_ids.h>
@@ -349,6 +350,17 @@ void rs780_enable(device_t dev)
 	}
 }
 
+#if !IS_ENABLED(CONFIG_AMD_SB_CIMX)
+unsigned long acpi_fill_mcfg(unsigned long current)
+{
+	/* FIXME
+	 * Leave table blank until proper contents
+	 * are determined.
+	 */
+	return current;
+}
+#endif
+
 struct chip_operations southbridge_amd_rs780_ops = {
 	CHIP_NAME("ATI RS780")
 	.enable_dev = rs780_enable,