usb: xhci: add quirks flag to support MediaTek xHCI 0.96

There some vendor quirks for MTK xHCI 0.96 host controller:
1. It defines some extra SW scheduling parameters for HW
   to minimize the scheduling effort for synchronous and
   interrupt endpoints. The parameters are put into reserved
   DWs of slot context and endpoint context.
2. Its TDS in  Normal TRB defines a number of packets that
   remains to be transferred for a TD after processing all
   Max packets in all previous TRBs.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Tested-by: Frank Wunderlich <frank-w@public-files.de>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>