usb/gadget: set our device as BUS-POWERED instead of SELF-POWERED

usb/gadget: set our device as BUS-POWERED instead of SELF-POWERED

BZ: 18296

Per compliance requirement, if USB device draws more than 100mA, it
should be set itself as a BUS-POWERED device.

Change-Id: I1a2033a9fad700a9cd0f945be3405ac502e4d143
Signed-off-by: Wu, Hao <hao.wu@intel.com>
Reviewed-on: http://android.intel.com:8080/29851
Reviewed-by: Zhuang, Jin Can <jin.can.zhuang@intel.com>
Reviewed-by: Tang, Richard <richard.tang@intel.com>
Reviewed-by: Meng, Zhe <zhe.meng@intel.com>
Tested-by: Meng, Zhe <zhe.meng@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>