nb/intel/i945: 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: I68848516fab2058d4aa96ac0342c883fd1df2d6d
Signed-off-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/39958
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
diff --git a/src/northbridge/intel/i945/gma.c b/src/northbridge/intel/i945/gma.c
index c26ffb4..f5a964a 100644
--- a/src/northbridge/intel/i945/gma.c
+++ b/src/northbridge/intel/i945/gma.c
@@ -755,25 +755,11 @@
 		pci_write_config8(dev, 0xf4, 0xff);
 }
 
-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(0x2, 0);
-	if (!dev)
-		return NULL;
-	struct northbridge_intel_i945_config *chip = dev->chip_info;
-	if (!chip)
-		return NULL;
-	return &chip->gfx;
-}
+	const struct northbridge_intel_i945_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 void gma_func0_read_resources(struct device *dev)
@@ -829,7 +815,7 @@
 	.set_resources		= pci_dev_set_resources,
 	.enable_resources	= pci_dev_enable_resources,
 	.init			= gma_func0_init,
-	.acpi_fill_ssdt		= gma_ssdt,
+	.acpi_fill_ssdt		= gma_generate_ssdt,
 	.scan_bus		= 0,
 	.enable			= 0,
 	.disable		= gma_func0_disable,