usb, dfu gadget: switch to dfu mode in dfu_bind

- set in to_dfu_mode() f_dfu->dfu_state = DFU_STATE_dfuIDLE
  as after every to_dfu_mode call this is done, so move
  this into to_dfu_mode
- switch in dfu_bind() into dfu mode:
  This fixes wrong "dfu-util -l" output, when calling
  "dfu-util -l" after a board reset, without doing a
  download before. See also discussion here:

http://lists.denx.de/pipermail/u-boot/2013-June/157272.html

Signed-off-by: Heiko Schocher <hs@denx.de>
Cc: Lukasz Majewski <l.majewski@samsung.com>
Cc: Pantelis Antoniou <panto@antoniou-consulting.com>
Cc: Tom Rini <trini@ti.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Marek Vasut <marex@denx.de>
Cc: Wolfgang Denk <wd@denx.de>
Cc: Samuel Egli <samuel.egli@siemens.com>
Acked-by: Lukasz Majewski <l.majewski@samsung.com>
Tested-by: Lukasz Majewski <l.majewski@samsung.com>

drivers/usb/gadget/f_dfu.c

@@ -183,6 +183,7 @@ static inline void to_dfu_mode(struct f_dfu *f_dfu)
 {
 	f_dfu->usb_function.strings = dfu_strings;
 	f_dfu->usb_function.hs_descriptors = f_dfu->function;
+	f_dfu->dfu_state = DFU_STATE_dfuIDLE;
 }
 
 static inline void to_runtime_mode(struct f_dfu *f_dfu)
@@ -233,7 +234,6 @@ static int state_app_idle(struct f_dfu *f_dfu,
 	case USB_REQ_DFU_DETACH:
 		f_dfu->dfu_state = DFU_STATE_appDETACH;
 		to_dfu_mode(f_dfu);
-		f_dfu->dfu_state = DFU_STATE_dfuIDLE;
 		value = RET_ZLP;
 		break;
 	default:
@@ -653,6 +653,8 @@ static int dfu_bind(struct usb_configuration *c, struct usb_function *f)
 			->iInterface = id;
 	}
 
+	to_dfu_mode(f_dfu);
+
 	stringtab_dfu.strings = f_dfu->strings;
 
 	cdev->req->context = f_dfu;