qdss_bridge: fix NULL usb_ch of usb_qdss_close

Status of opened "ENABLE" cannot guarantee that usb_ch is not NULL when
calling usb_qdss_open failed, this change modifies status of opened to
"ENABLE" only when calling usb_qdss_open successful.

Change-Id: I946e057a21611c372af140af308fd03dcfcd6430
Signed-off-by: Yuanfang Zhang <zhangyuanfang@codeaurora.org>