usb: gadget: should use u16 type variable to store MaxPower

From 7e827a0d300e084f74c65122baa5e3193f9a7f18 Mon Sep 17 00:00:00 2001
From: "Du, Changbin" <changbinx.du@intel.com>
Date: Mon, 16 Dec 2013 20:32:13 +0800
Subject: [PATCH] usb/gadget: should use u16 type variable to store MaxPower

The MaxPower field is of u16 type. So using u8 type variable can break
data (high byte lost).

Signed-off-by: Du, Changbin <changbinx.du@intel.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>