coresight: byte-cnter: Add ETR status check in bypass notifier

when usb_bypass_notify is called by ush_qdss_close(), no need to
response to USB_QDSS_DISCONNECT event. so add etr status check to
avoid exception.

Change-Id: I4ab5d7f4ba054b0d1ecc7026b5662ddc1c8b5ca1
Signed-off-by: Yuanfang Zhang <zhangyuanfang@codeaurora.org>