nb/intel/sandybridge: Simplify GMA SSDT generator

Simplify generation of GMA SSDT, using updated naming convention.
If acpi_fill_ssdt is being invoked, then we know the IGD device is
present and enabled, so we can skip those checks. And the SSDT
generator now checks that the gfx struct is populated, so we can
skip that too.

Change-Id: If34ebe0edc46674244c9d5afc7ed165c2ad685ba
Signed-off-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/39949
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
diff --git a/src/northbridge/intel/sandybridge/gma.c b/src/northbridge/intel/sandybridge/gma.c
index e79277c..b68e705 100644
--- a/src/northbridge/intel/sandybridge/gma.c
+++ b/src/northbridge/intel/sandybridge/gma.c
@@ -640,24 +640,11 @@
 	intel_gma_restore_opregion();
 }
 
-const struct i915_gpu_controller_info *intel_gma_get_controller_info(void)
+static void gma_generate_ssdt(struct device *device)
 {
-	struct device *dev = pcidev_on_root(2, 0);
-	if (!dev) {
-		return NULL;
-	}
-	struct northbridge_intel_sandybridge_config *chip = dev->chip_info;
-	return &chip->gfx;
-}
+	const struct northbridge_intel_sandybridge_config *chip = device->chip_info;
 
-static void gma_ssdt(struct device *device)
-{
-	const struct i915_gpu_controller_info *gfx = intel_gma_get_controller_info();
-	if (!gfx) {
-		return;
-	}
-
-	drivers_intel_gma_displays_ssdt_generate(gfx);
+	drivers_intel_gma_displays_ssdt_generate(&chip->gfx);
 }
 
 static unsigned long gma_write_acpi_tables(struct device *const dev, unsigned long current,
@@ -710,7 +697,7 @@
 	.read_resources         = pci_dev_read_resources,
 	.set_resources          = pci_dev_set_resources,
 	.enable_resources       = pci_dev_enable_resources,
-	.acpi_fill_ssdt		= gma_ssdt,
+	.acpi_fill_ssdt		= gma_generate_ssdt,
 	.init                   = gma_func0_init,
 	.scan_bus               = NULL,
 	.enable                 = NULL,