usb: gadget: introduce is_selfpowered for usb_gadget

Whether the gadget is selfpowerwed or not can be determined by composite
core, so we can use a common entry to indicate if the self-powered
is supported by gadget, and the related private variable at individual
udc driver can be deleted.
Signed-off-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

include/linux/usb/gadget.h

@@ -523,6 +523,7 @@ struct usb_gadget_ops {
  *	enabled HNP support.
  * @quirk_ep_out_aligned_size: epout requires buffer size to be aligned to
  *	MaxPacketSize.
+ * @is_selfpowered: if the gadget is self-powered.
  *
  * Gadgets have a mostly-portable "gadget driver" implementing device
  * functions, handling all usb configurations and interfaces.  Gadget
@@ -563,6 +564,7 @@ struct usb_gadget {
 	unsigned			a_hnp_support:1;
 	unsigned			a_alt_hnp_support:1;
 	unsigned			quirk_ep_out_aligned_size:1;
+	unsigned			is_selfpowered:1;
 };
 #define work_to_gadget(w)	(container_of((w), struct usb_gadget, work))