usb: gadget: configure endpoint according to gadget speed

Add config_ep_by_speed() to configure the endpoint
according to the gadget speed.

Using this function will spare the FDs from handling
the endpoint chosen descriptor.

Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

include/linux/usb/gadget.h

@@ -133,6 +133,8 @@ struct usb_ep_ops {
  *	value can sometimes be reduced (hardware allowing), according to
  *      the endpoint descriptor used to configure the endpoint.
  * @driver_data:for use by the gadget driver.
+ * @address: used to identify the endpoint when finding descriptor that
+ *	matches connection speed
  * @desc: endpoint descriptor.  This pointer is set before the endpoint is
  *	enabled and remains valid until the endpoint is disabled.
  *
@@ -147,6 +149,7 @@ struct usb_ep {
 	const struct usb_ep_ops	*ops;
 	struct list_head	ep_list;
 	unsigned		maxpacket:16;
+	u8			address;
 	const struct usb_endpoint_descriptor	*desc;
 };