USB: gadget: qdss: Add check before performing uninit_data()

Currently init_data() is performed from usb_qdss_connect_work()
context which schedules only when QDSS interface(STM or ETM) is
being enabled by user and usb_qdss_open() is being called, whereas
uninit_data() is performed from usb_qdss_disconnect_work() context
called from qdss_disable(). If user is not enabling QDSS interface
(STM or ETM), and performing composition switch from QDSS based
USB composition, we try to unconfig msm specific endpoint operation
which fails showing error message as usb_qdss_connect_work() is not
being scheduled. Hence add check for QDSS interface is being opened
or not in usb_qdss_disconnect_work() to handle this case.

Change-Id: I7058733873f3e09d6c2ff28c9d10d9214506f0ef
Signed-off-by: Mayank Rana <mrana@codeaurora.org>