usb: gadget: fastboot: Set the Serial Number for Fastboot Gadget

Configure the serial number using the serial# environment variable
during the fastboot bind.

This enables "fastboot devices" to return the serial number for
the attached devices.

Signed-off-by: Dileep Katta <dileep.katta@linaro.org>
Acked-by: Steve Rae <srae@broadcom.com>
Reviewed-by: Lukasz Majewski <l.majewski@samsung.com>

drivers/usb/gadget/f_fastboot.c

@@ -137,6 +137,7 @@ static int fastboot_bind(struct usb_configuration *c, struct usb_function *f)
 	int id;
 	struct usb_gadget *gadget = c->cdev->gadget;
 	struct f_fastboot *f_fb = func_to_fastboot(f);
+	const char *s;
 
 	/* DYNAMIC interface numbers assignments */
 	id = usb_interface_id(c, f);
@@ -162,6 +163,10 @@ static int fastboot_bind(struct usb_configuration *c, struct usb_function *f)
 
 	hs_ep_out.bEndpointAddress = fs_ep_out.bEndpointAddress;
 
+	s = getenv("serial#");
+	if (s)
+		g_dnl_set_serialnumber((char *)s);
+
 	return 0;
 }