soc/amd/common/block/graphics/graphics: Add missing const to fill_ssdt

BUG=none
TEST=Made sure trembyle builds

Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Change-Id: I9df70fd5c41a9a68edc7be3c2e920c4dc94d5af9
Reviewed-on: https://review.coreboot.org/c/coreboot/+/40871
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/soc/amd/common/block/graphics/graphics.c b/src/soc/amd/common/block/graphics/graphics.c
index a40aadd..6715a43 100644
--- a/src/soc/amd/common/block/graphics/graphics.c
+++ b/src/soc/amd/common/block/graphics/graphics.c
@@ -5,7 +5,7 @@
 #include <device/pci.h>
 #include <device/pci_ids.h>
 
-static void graphics_fill_ssdt(struct device *dev)
+static void graphics_fill_ssdt(const struct device *dev)
 {
 	acpi_device_write_pci_dev(dev);
 	pci_rom_ssdt(dev);