device: Constify struct device * parameter to acpi_fill_ssdt()

.acpi_fill_ssdt() does not need to modify the device structure. This
change makes the struct device * parameter to acpi_fill_ssdt() as
const.

Change-Id: I110f4c67c3b6671c9ac0a82e02609902a8ee5d5c
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/40710
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/northbridge/intel/x4x/gma.c b/src/northbridge/intel/x4x/gma.c
index c1b7837..03d7264 100644
--- a/src/northbridge/intel/x4x/gma.c
+++ b/src/northbridge/intel/x4x/gma.c
@@ -80,7 +80,7 @@
 	pci_write_config16(dev_host, D0F0_GGC, ggc);
 }
 
-static void gma_generate_ssdt(struct device *device)
+static void gma_generate_ssdt(const struct device *device)
 {
 	const struct northbridge_intel_x4x_config *chip = device->chip_info;