USB: dwc3-msm: Disable DBM endpoint in msm_ep_unconfig if no req queued

There is a chance that error might occur in connect_work before
endless request is queued to USB controller and bails out. In this case,
DBM endpoint will not be disabled and results in setendpoint config
command timeouts after next connect and could cause usb endpoint enable
fails. Fix this by disabling DBM endpoint corresponding to USB endpoint
in msm_ep_unconfig() if there are no requests queued to USB endpoint.

Change-Id: I5601d76c58263150a3ad5b026a8f2b10da087ba5
Signed-off-by: Vijayavardhan Vennapusa <vvreddy@codeaurora.org>
Signed-off-by: Chandana Kishori Chiluveru <cchiluve@codeaurora.org>
Signed-off-by: Sriharsha Allenki <sallenki@codeaurora.org>