Lock must be taken before calling dwc_scan_descriptors, as this may
access/modify shared data and queues. dwc_tx_status wasn't taking lock before
calling this routine. This patch add code that takes lock before calling
dwc_scan_descriptors.
Signed-off-by: NViresh Kumar <viresh.kumar@st.com>
Signed-off-by: NVinod Koul <vinod.koul@intel.com>