usb: xhci-mtk: allow multiple Start-Split in a microframe

This patch is used to relax bandwidth schedule by allowing multiple
Start-Split in the same microframe.

Reviewed-and-Tested-by: Ikjoon Jang <ikjn@chromium.org>
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/1623995165-25759-1-git-send-email-chunfeng.yun@mediatek.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>