dm: core: Allow finding a uclass device by partial name

In some cases two devices are related and the only way to tell is to
check that the names partially patch. Add a way to check this without
needing to create a new string for the comparison.

Fix the comment for device_find_child_by_namelen() while we are here.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/core/uclass.c b/drivers/core/uclass.c
index 4b9b54f..08d9ed8 100644
--- a/drivers/core/uclass.c
+++ b/drivers/core/uclass.c
@@ -274,8 +274,8 @@
 	return 0;
 }
 
-int uclass_find_device_by_name(enum uclass_id id, const char *name,
-			       struct udevice **devp)
+int uclass_find_device_by_namelen(enum uclass_id id, const char *name, int len,
+				  struct udevice **devp)
 {
 	struct uclass *uc;
 	struct udevice *dev;
@@ -289,7 +289,8 @@
 		return ret;
 
 	uclass_foreach_dev(dev, uc) {
-		if (!strcmp(dev->name, name)) {
+		if (!strncmp(dev->name, name, len) &&
+		    strlen(dev->name) == len) {
 			*devp = dev;
 			return 0;
 		}
@@ -298,6 +299,12 @@
 	return -ENODEV;
 }
 
+int uclass_find_device_by_name(enum uclass_id id, const char *name,
+			       struct udevice **devp)
+{
+	return uclass_find_device_by_namelen(id, name, strlen(name), devp);
+}
+
 int uclass_find_next_free_seq(struct uclass *uc)
 {
 	struct udevice *dev;