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/drivers/generic/gpio_keys/gpio_keys.c b/src/drivers/generic/gpio_keys/gpio_keys.c
index b8e72bf..1017f7a 100644
--- a/src/drivers/generic/gpio_keys/gpio_keys.c
+++ b/src/drivers/generic/gpio_keys/gpio_keys.c
@@ -46,7 +46,7 @@
 	return dsd;
 }
 
-static void gpio_keys_fill_ssdt_generator(struct device *dev)
+static void gpio_keys_fill_ssdt_generator(const struct device *dev)
 {
 	struct drivers_generic_gpio_keys_config *config = dev->chip_info;
 	const char *scope = acpi_device_scope(dev);