ACPI: PCC: pcc_ctx can be static

drivers/acpi/acpi_pcc.c:34:22: warning: symbol 'pcc_ctx' was not declared. Should it be static?
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: kernel test robot <lkp@intel.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/acpi_pcc.c

@@ -31,7 +31,7 @@ struct pcc_data {
 	struct acpi_pcc_info ctx;
 };
 
-struct acpi_pcc_info pcc_ctx;
+static struct acpi_pcc_info pcc_ctx;
 
 static void pcc_rx_callback(struct mbox_client *cl, void *m)
 {