amd/gardenia: Add AHB bridge registers in ACPI

Add the region used by the A-Link to AHB configuration registers.

Original-Signed-off-by: Marshall Dawson <marshalldawson3rd@gmail.com>
Original-Reviewed-by: Marc Jones <marcj303@gmail.com>
(squashed from 2c8dafdf44cf1a84cbc25e8aa381c04c160ee705
           and 3c755f70ffa36c0fc92a1da0e3f5f877c8dc9e8b)

Change-Id: I7398452c6e70b4545e16398f3fec157f2f30293a
Signed-off-by: Marshall Dawson <marshalldawson3rd@gmail.com>
Reviewed-on: https://review.coreboot.org/17848
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>

src/mainboard/amd/gardenia/acpi/carrizo_fch.asl

@@ -13,6 +13,20 @@
  * GNU General Public License for more details.
  */
 
+Device(AAHB) {
+	Name(_HID,"AAHB0000")
+	Name(_UID,0x0)
+	Name(_CRS, ResourceTemplate()
+	{
+		IRQ(Edge, ActiveHigh, Exclusive) {7}
+		Memory32Fixed(ReadWrite, 0xFEDC0000, 0x2000)
+	})
+
+	Method (_STA, 0x0, NotSerialized) {
+		Return (0x0F)
+	}
+}
+
 Device(GPIO) {
 	Name (_HID, "AMD0030")
 	Name (_CID, "AMD0030")