usb: fix building musb drivers

Commit 3dacdf11 "usb: factor out state_string() on otg drivers"
broke building musb drivers since there is already another
otg_state_string() function in musb drivers, but with different
prototype. Fix musb drivers to use common otg_state_string(), too.

Also provide a nop for otg_state_string() if CONFIG_USB_OTG_UTILS
is not defined.

Signed-off-by: Anatolij Gustschin <agust@denx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c
index 5eef4a8..07b106c 100644
--- a/drivers/usb/musb/musb_host.c
+++ b/drivers/usb/musb/musb_host.c
@@ -2304,7 +2304,7 @@
 
 	if (musb->is_active) {
 		WARNING("trying to suspend as %s while active\n",
-				otg_state_string(musb));
+				otg_state_string(musb->xceiv->state));
 		return -EBUSY;
 	} else
 		return 0;