usb: otg: prefix otg_state_string with usb_

all other functions under drivers/usb/ start
with usb_, let's do the same thing.

This patch is in preparation for moving otg_state_string
to usb-common.c and deleting otg.c completely.

Signed-off-by: Felipe Balbi <balbi@ti.com>
diff --git a/drivers/usb/musb/musb_gadget.c b/drivers/usb/musb/musb_gadget.c
index 6101ebf..e840888 100644
--- a/drivers/usb/musb/musb_gadget.c
+++ b/drivers/usb/musb/musb_gadget.c
@@ -1571,7 +1571,7 @@
 		goto done;
 	default:
 		dev_dbg(musb->controller, "Unhandled wake: %s\n",
-			otg_state_string(musb->xceiv->state));
+			usb_otg_state_string(musb->xceiv->state));
 		goto done;
 	}
 
@@ -1970,7 +1970,7 @@
 		break;
 	default:
 		WARNING("unhandled RESUME transition (%s)\n",
-				otg_state_string(musb->xceiv->state));
+				usb_otg_state_string(musb->xceiv->state));
 	}
 }
 
@@ -2000,7 +2000,7 @@
 		 * A_PERIPHERAL may need care too
 		 */
 		WARNING("unhandled SUSPEND transition (%s)\n",
-				otg_state_string(musb->xceiv->state));
+				usb_otg_state_string(musb->xceiv->state));
 	}
 }
 
@@ -2034,7 +2034,7 @@
 	switch (musb->xceiv->state) {
 	default:
 		dev_dbg(musb->controller, "Unhandled disconnect %s, setting a_idle\n",
-			otg_state_string(musb->xceiv->state));
+			usb_otg_state_string(musb->xceiv->state));
 		musb->xceiv->state = OTG_STATE_A_IDLE;
 		MUSB_HST_MODE(musb);
 		break;