usb: gadget: use usb_string_ids_tab instead multiple usb_string_id()

Using usb_string_ids_tab() instead multiple calls of usb_string_id()
seems to be handy. It also allows to add string without many checks.

Acked-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>
diff --git a/drivers/usb/gadget/webcam.c b/drivers/usb/gadget/webcam.c
index 66dfca8..d44a451 100644
--- a/drivers/usb/gadget/webcam.c
+++ b/drivers/usb/gadget/webcam.c
@@ -355,20 +355,15 @@
 	/* Allocate string descriptor numbers ... note that string contents
 	 * can be overridden by the composite_dev glue.
 	 */
-	if ((ret = usb_string_id(cdev)) < 0)
+	ret = usb_string_ids_tab(cdev, webcam_strings);
+	if (ret < 0)
 		goto error;
-	webcam_strings[STRING_MANUFACTURER_IDX].id = ret;
-	webcam_device_descriptor.iManufacturer = ret;
-
-	if ((ret = usb_string_id(cdev)) < 0)
-		goto error;
-	webcam_strings[STRING_PRODUCT_IDX].id = ret;
-	webcam_device_descriptor.iProduct = ret;
-
-	if ((ret = usb_string_id(cdev)) < 0)
-		goto error;
-	webcam_strings[STRING_DESCRIPTION_IDX].id = ret;
-	webcam_config_driver.iConfiguration = ret;
+	webcam_device_descriptor.iManufacturer =
+		webcam_strings[STRING_MANUFACTURER_IDX].id;
+	webcam_device_descriptor.iProduct =
+		webcam_strings[STRING_PRODUCT_IDX].id;
+	webcam_config_driver.iConfiguration =
+		webcam_strings[STRING_DESCRIPTION_IDX].id;
 
 	/* Register our configuration. */
 	if ((ret = usb_add_config(cdev, &webcam_config_driver,