dm: cpu: Add a new get_count method to cpu uclass

Introduce a new method 'get_count' in the UCLASS_CPU ops to get
the number of CPUs in the system.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/cpu/cpu-uclass.c b/drivers/cpu/cpu-uclass.c
index d6be9d4..a2814a8 100644
--- a/drivers/cpu/cpu-uclass.c
+++ b/drivers/cpu/cpu-uclass.c
@@ -32,6 +32,16 @@
 	return ops->get_info(dev, info);
 }
 
+int cpu_get_count(struct udevice *dev)
+{
+	struct cpu_ops *ops = cpu_get_ops(dev);
+
+	if (!ops->get_count)
+		return -ENOSYS;
+
+	return ops->get_count(dev);
+}
+
 U_BOOT_DRIVER(cpu_bus) = {
 	.name	= "cpu_bus",
 	.id	= UCLASS_SIMPLE_BUS,