gm45: Declare brightness variables for ACPI use.

Change-Id: I23a088919aaac16066e5dd8300a081a8095a93f0
Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com>
Reviewed-on: http://review.coreboot.org/6589
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>

src/northbridge/intel/gm45/acpi/igd.asl

@@ -23,6 +23,22 @@ Device (GFX0)
 {
 	Name (_ADR, 0x00020000)
 
+	OperationRegion (GFXC, PCI_Config, 0x00, 0x0100)
+	Field (GFXC, DWordAcc, NoLock, Preserve)
+	{
+		Offset (0x10),
+		BAR0, 64
+        }
+
+	OperationRegion (GFRG, SystemMemory, And (BAR0, 0xfffffffffffffff0), 0x400000)
+	Field (GFRG, DWordAcc, NoLock, Preserve)
+	{
+		Offset (0x61250),
+			CR1, 32,
+			BCLV, 16,
+			BCLM, 16,
+	}
+
 	/* Display Output Switching */
 	Method (_DOS, 1)
 	{