usb: musb: Prevent the masking of the return value

Currently the errors returned by fifo_setup get masked
by EINVAL, propagate the same to the caller.

Signed-off-by: Shubhrajyoti D <shubhrajyoti@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/musb/musb_core.c

@@ -1295,7 +1295,7 @@ done:
 		if (offset < 0) {
 			pr_debug("%s: mem overrun, ep %d\n",
 					musb_driver_name, epn);
-			return -EINVAL;
+			return offset;
 		}
 		epn++;
 		musb->nr_endpoints = max(epn, musb->nr_endpoints);