usb: xhci-mtk: skip dropping bandwidth of unchecked endpoints

For those unchecked endpoints, we don't allocate bandwidth for
them, so no need free the bandwidth, otherwise will decrease
the allocated bandwidth.
Meanwhile use xhci_dbg() instead of dev_dbg() to print logs and
rename bw_ep_list_new as bw_ep_chk_list.

Fixes: 1d69f9d9

 ("usb: xhci-mtk: fix unreleased bandwidth data")
Cc: stable <stable@vger.kernel.org>
Reviewed-and-tested-by: Ikjoon Jang <ikjn@chromium.org>
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/1612159064-28413-1-git-send-email-chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>