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>

src/cpu/intel/model_206ax/acpi.c

@@ -284,7 +284,7 @@ static void generate_P_state_entries(int core, int cores_per_package)
 	acpigen_pop_len();
 }
 
-void generate_cpu_entries(struct device *device)
+void generate_cpu_entries(const struct device *device)
 {
 	int coreID, cpuID, pcontrol_blk = PMB0_BASE, plen = 6;
 	int totalcores = dev_count_cpu();