USB: gadget: Add association descriptor for windows

USB: gadget: Add association descriptor for windows

BZ: 19004

This patch adds USB association descriptor supporting Android
ACM in windows. The descriptor presents itself as "CDC Serial"
device to PC in order to match the proper driver in windows.

Change-Id: I05a4cee6023fe10375b367e1beafd78214c5e9f3
Signed-off-by: Liu, DongxingX <dongxingx.liu@intel.com>
Reviewed-on: http://android.intel.com:8080/31150
Reviewed-by: Tang, Richard <richard.tang@intel.com>
Reviewed-by: Alagnou, GregoryX <gregoryx.alagnou@intel.com>
Tested-by: Sun, Jianhua <jianhua.sun@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>