usb: xhci-mtk: fix issue of out-of-bounds array access

commit de5107f4 upstream.

Bus bandwidth array access is based on esit, increase one
will cause out-of-bounds issue; for example, when esit is
XHCI_MTK_MAX_ESIT, will overstep boundary.

Fixes: 7c986fbc

 ("usb: xhci-mtk: get the microframe boundary for ESIT")
Cc: <stable@vger.kernel.org>
Reported-by: Stan Lu <stan.lu@mediatek.com>
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/1629189389-18779-5-git-send-email-chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>