cpu: Convert the methods to use a const udevice *

These functions should not modify the device. Convert them to const so
that callers don't need to cast if they have a const udevice *.

Signed-off-by: Simon Glass <sjg@chromium.org>

drivers/cpu/cpu-uclass.c

@@ -69,7 +69,7 @@ struct udevice *cpu_get_current_dev(void)
 	return cpu;
 }
 
-int cpu_get_desc(struct udevice *dev, char *buf, int size)
+int cpu_get_desc(const struct udevice *dev, char *buf, int size)
 {
 	struct cpu_ops *ops = cpu_get_ops(dev);
 
@@ -79,7 +79,7 @@ int cpu_get_desc(struct udevice *dev, char *buf, int size)
 	return ops->get_desc(dev, buf, size);
 }
 
-int cpu_get_info(struct udevice *dev, struct cpu_info *info)
+int cpu_get_info(const struct udevice *dev, struct cpu_info *info)
 {
 	struct cpu_ops *ops = cpu_get_ops(dev);
 
@@ -92,7 +92,7 @@ int cpu_get_info(struct udevice *dev, struct cpu_info *info)
 	return ops->get_info(dev, info);
 }
 
-int cpu_get_count(struct udevice *dev)
+int cpu_get_count(const struct udevice *dev)
 {
 	struct cpu_ops *ops = cpu_get_ops(dev);
 
@@ -102,7 +102,7 @@ int cpu_get_count(struct udevice *dev)
 	return ops->get_count(dev);
 }
 
-int cpu_get_vendor(struct udevice *dev, char *buf, int size)
+int cpu_get_vendor(const struct udevice *dev, char *buf, int size)
 {
 	struct cpu_ops *ops = cpu_get_ops(dev);