usb: gadget: Weak board_usb_init/cleanup definitions in USB download gadget code

Weak versions of board_usb_init and board_usb_cleanup are defined in common USB
host code, but it is also used for USB device gadgets, so we also need a weak
definition of it when there is no USB host enabled.
Both weak definitions do not conflict.

Signed-off-by: Paul Kocialkowski <contact@paulk.fr>
Tested-by: Lukasz Majewski <l.majewski@samsung.com>

Test HW: Odroid_XU3 (Exynos5422), trats (Exynos4210)
diff --git a/drivers/usb/gadget/g_dnl.c b/drivers/usb/gadget/g_dnl.c
index ee52a29..ad89a0d 100644
--- a/drivers/usb/gadget/g_dnl.c
+++ b/drivers/usb/gadget/g_dnl.c
@@ -12,6 +12,7 @@
 
 #include <mmc.h>
 #include <part.h>
+#include <usb.h>
 
 #include <g_dnl.h>
 #include <usb_mass_storage.h>
@@ -148,6 +149,18 @@
 }
 
 __weak
+int board_usb_init(int index, enum usb_init_type init)
+{
+	return 0;
+}
+
+__weak
+int board_usb_cleanup(int index, enum usb_init_type init)
+{
+	return 0;
+}
+
+__weak
 int g_dnl_bind_fixup(struct usb_device_descriptor *dev, const char *name)
 {
 	return 0;