usb: squash lines for immediate return

This makes functions much simpler.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/common/usb_kbd.c b/common/usb_kbd.c
index 97f79f8..a9872a6 100644
--- a/common/usb_kbd.c
+++ b/common/usb_kbd.c
@@ -605,11 +605,8 @@
 static int usb_kbd_probe(struct udevice *dev)
 {
 	struct usb_device *udev = dev_get_parent_priv(dev);
-	int ret;
-
-	ret = probe_usb_keyboard(udev);
 
-	return ret;
+	return probe_usb_keyboard(udev);
 }
 
 static int usb_kbd_remove(struct udevice *dev)