device: Constify struct device * parameter to write_acpi_tables

.write_acpi_tables() should not be updating the device structure. This
change makes the struct device * argument to it as const.

Change-Id: I50d013e83a404e0a0e3837ca16fa75c7eaa0e14a
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/40701
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Raul Rangel <rrangel@chromium.org>

src/soc/intel/skylake/graphics.c

@@ -147,7 +147,7 @@ static void update_igd_opregion(igd_opregion_t *opregion)
 	/* FIXME: Add platform specific mailbox initialization */
 }
 
-uintptr_t graphics_soc_write_acpi_opregion(struct device *device,
+uintptr_t graphics_soc_write_acpi_opregion(const struct device *device,
 		uintptr_t current, struct acpi_rsdp *rsdp)
 {
 	igd_opregion_t *opregion;