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/omap2430.c b/drivers/usb/musb/omap2430.c
index 1a42a45..8ba9bb2 100644
--- a/drivers/usb/musb/omap2430.c
+++ b/drivers/usb/musb/omap2430.c
@@ -117,7 +117,7 @@
 	if (musb->is_active || ((musb->a_wait_bcon == 0)
 			&& (musb->xceiv->state == OTG_STATE_A_WAIT_BCON))) {
 		dev_dbg(musb->controller, "%s active, deleting timer\n",
-			otg_state_string(musb->xceiv->state));
+			usb_otg_state_string(musb->xceiv->state));
 		del_timer(&musb_idle_timer);
 		last_timer = jiffies;
 		return;
@@ -134,7 +134,7 @@
 	last_timer = timeout;
 
 	dev_dbg(musb->controller, "%s inactive, for idle timer for %lu ms\n",
-		otg_state_string(musb->xceiv->state),
+		usb_otg_state_string(musb->xceiv->state),
 		(unsigned long)jiffies_to_msecs(timeout - jiffies));
 	mod_timer(&musb_idle_timer, timeout);
 }
@@ -200,7 +200,7 @@
 
 	dev_dbg(musb->controller, "VBUS %s, devctl %02x "
 		/* otg %3x conf %08x prcm %08x */ "\n",
-		otg_state_string(musb->xceiv->state),
+		usb_otg_state_string(musb->xceiv->state),
 		musb_readb(musb->mregs, MUSB_DEVCTL));
 }