USB: gadget: composite: Don't call set_alt() on functions that are hidden.

Signed-off-by: Mike Lockwood <lockwood@android.com>
diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index 46a6508..cf7a5cf 100644
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -484,6 +484,8 @@
 
 		if (!f)
 			break;
+		if (f->hidden)
+			continue;
 
 		/*
 		 * Record which endpoints are used by the function. This is used